xtb

https://xtb-docs.readthedocs.io/en/latest/
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xtb is an extended tight-binding semiempirical quantum mechanical program package designed for the...
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### Review Calculation Setup Output

Source: https://xtb-docs.readthedocs.io/en/latest/xtb_docking.html

Example of the console output displayed when starting the docking calculation.

```text
 -------------------------------------------------
|                Calculation Setup                |
 -------------------------------------------------


program call               : xtb dock molecule1.xyz molecule2.xyz
omp threads                :                    12
coordinate file A          : molecule1.xyz
coordinate file B          : molecule2.xyz
number of atoms A          :                    26
number of atoms B          :                    15
charge of molecule A       :                   1.0
charge of molecule B       :                  -1.0
spin of molecule A         :                     0
spin of molecule B         :                     0
first test random number   :      0.24945994848576
```

--------------------------------

### Calculation Setup Output

Source: https://xtb-docs.readthedocs.io/en/latest/_sources/sp.rst.txt

Example of the Calculation Setup section in the output file.

```none
        -------------------------------------------------
       |                Calculation Setup                |
        -------------------------------------------------

       program call               : xtb molecule.xyz
       hostname                   : user
       coordinate file            : molecule.xyz
       omp threads                :                     4
       number of atoms            :                     3
       number of electrons        :                     7
       charge                     :                     1    # Specified molecular charge
       spin                       :                   1.0    # Total spin from number of unpaired electrons (S=2*0.5=1)
       first test random number   :      0.54680533077496
```

--------------------------------

### ANCopt setup output

Source: https://xtb-docs.readthedocs.io/en/latest/_sources/optimization.rst.txt

Example of the optimization configuration summary printed by xtb during execution.

```text
	      -----------------------------------------------------------
	     |                   =====================                   |
	     |                        A N C O P T                        |
	     |                   =====================                   |
	     |               Approximate Normal Coordinate               |
	     |                Rational Function Optimizer                |
	      -----------------------------------------------------------

		  ...................................................
		  :                      SETUP                      :
		  :.................................................:
		  :   optimization level            normal          :
		  :   max. optcycles                   200          :
		  :   ANC micro-cycles                  20          :
		  :   degrees of freedom                 7          :
		  :.................................................:
		  :   RF solver                      spevx          :
		  :   input Hessian                  false          :
		  :   write xtbopt.log                true          :
		  :   linear (good luck)              true          :
		  :   energy convergence         0.5000000E-05 Eh   :
		  :   grad. convergence          0.1000000E-02 Eh/Î± :
		  :   maximium RF displ.         1.0000000          :
		  :   Hlow (freq-cutoff)         0.2000000E-01      :
		  :   Hmax (freq-cutoff)         5.0000000          :
		  :   S6 in model hess.         20.0000000          :
		  ...................................................
```

--------------------------------

### Install the build

Source: https://xtb-docs.readthedocs.io/en/latest/development.html

Perform the installation of the compiled binaries.

```bash
ninja -C build install
```

--------------------------------

### Configure and Install xtb

Source: https://xtb-docs.readthedocs.io/en/latest/_sources/development.rst.txt

Set the installation prefix and perform the installation of the compiled binaries.

```none
meson configure build --prefix=$HOME/.local
```

```none
ninja -C build install
```

--------------------------------

### Standard Output for PTB

Source: https://xtb-docs.readthedocs.io/en/latest/ptb.html

Example output showing the PTB calculation progress and setup parameters.

```text
           -------------------------------------------------
          |                      P T B                      |
           -------------------------------------------------

        Reference                      10.1063/5.0137838

 @@@@@@@@@@@@@@@@@@@@@@@@@@@@@
 @,,,,,,,,,,,,,,,,,,,,,,,,,,,,@@
 @,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,@
 @,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,*
 @,,,,,,,,@///////////////#,,,,,,,,,@
 @,,,,,,,,@/////////////////,,,,,,,,(
 @,,,,,,,,@/////////////////,,,,,,,,(
 @,,,,,,,,@/////////////////,,,,,,,,(
 @,,,,,,,,@/////////////////,,,,,,,,(
 @,,,,,,,,@/////////////////,,,,,,,,(
 @,,,,,,,,@/////////////////,,,,,,,,(
 @,,,,,,,,@////////////////@,,,,,,,,@
 @,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,%   @@@@@@@@@@@@@@@@@@   @@@@@@@@@@@@@@
 @,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,&////@,,,,,,,,,,,,,,,,,///@,,,,,,,,,,,,,,@
 @,,,,,,,,,,,,,,,,,,,,,,,,,,,,,@///////@,,,,,,,,,,,,,,,,,,//@,,,,,,,,,,,,,,,,@
 @,,,,,,,,@///////////////////////////////////@,,,#/////////@,,,@////////*,,,@
 @,,,,,,,,@/////////@ ////////////////////////@,,,#/////////@,,,@////////*,,,@
 @,,,,,,,,@///// %@@  ( @@@ (@ @@@ @//////////@,,,#/////////@,,,@////////*,,,@
 @,,,,,,,,@////( @//@ ( @@@ @@ @//.@//////////@,,,#/////////@,,,,,,,,,,,,,,,*
 @,,,,,,,,@///// @//@ ( @////@ @//.@//////////@,,,#/////////@,,,,,,,,,,,,,,,,@
 @,,,,,,,,@//////@@@@@/(@@@@/@@@//@@//////////@,,,#/////////@,,,@////////(,,,,@
 @,,,,,,,,@///////////#@@/ @//////////////////@,,,#/////////@,,,@/////////,,,,@
 @,,,,,,,,@//// .@@/(/# @@ @@/@ /// @/////////@,,,#/////////@,,,@/////////,,,,@
 @,,,,,,,,@////%    @/# @/ @//@ /// @/////////@,,,#/////////@,,,@////////@,,,,@
 @,,,,,,,,@////////@ /# @/ @//@ /// @/////////@,,,#/////////@,,,,,,,,,,,,,,,,@
 &@@@@@@@@@/////@@@@//(@@/#@@(/#@@@ @
                              @@@ @


          ...................................................
          :                      SETUP                      :
          :.................................................:
          :  # atomic orbitals                 250          :
          :  # shells                          108          :
          :  # electrons                        76          :
          :  # open shells                       0          :
          :  max. iterations                     2          :
          :  Hamiltonian                       PTB          :
          :  PC potential                    false          :
          :  electronic temp.          300.0000000     K    :
          :  -> integral cutoff          0.2500000E+02      :
          :  verbosity level                     2          :
          ...................................................

          --- Calculation progress: ---
              1st iteration...
              2nd iteration...
          --- Two-step SCF done. ---

           -------------------------------------------------
          |                Property Printout                |
           -------------------------------------------------

    * Orbital Energies and Occupations
```

--------------------------------

### Compile and Install Project

Source: https://xtb-docs.readthedocs.io/en/latest/_sources/development.rst.txt

Build and install the project using the ninja build system.

```bash
ninja -C build_gpu install
```

--------------------------------

### Optimization setup output

Source: https://xtb-docs.readthedocs.io/en/latest/optimization.html

The configuration summary printed by the optimizer at the start of the process.

```text
 -----------------------------------------------------------
|                   =====================                   |
|                        A N C O P T                        |
|                   =====================                   |
|               Approximate Normal Coordinate               |
|                Rational Function Optimizer                |
 -----------------------------------------------------------

     ...................................................
     :                      SETUP                      :
     :.................................................:
     :   optimization level            normal          :
     :   max. optcycles                   200          :
     :   ANC micro-cycles                  20          :
     :   degrees of freedom                 7          :
     :.................................................:
     :   RF solver                      spevx          :
     :   input Hessian                  false          :
     :   write xtbopt.log                true          :
     :   linear (good luck)              true          :
     :   energy convergence         0.5000000E-05 Eh   :
     :   grad. convergence          0.1000000E-02 Eh/α :
     :   maximium RF displ.         1.0000000          :
     :   Hlow (freq-cutoff)         0.2000000E-01      :
     :   Hmax (freq-cutoff)         5.0000000          :
     :   S6 in model hess.         20.0000000          :
     ...................................................
```

--------------------------------

### Example ONIOM Calculation Output

Source: https://xtb-docs.readthedocs.io/en/latest/_sources/oniom.rst.txt

Sample output showing the calculation setup and atom distribution for an ONIOM run.

```none
              -------------------------------------------------
             |                Calculation Setup                |
              -------------------------------------------------

             program call               : xtb input.xyz --oniom orca:gfn2 1-62 --chrg +1 --cut
             hostname                   : albert
             coordinate file            : input.xyz
             omp threads                :                    16

      ID    Z sym.   atoms
       1    6 C      1-30, 63-68, 73-81
       2    7 N      31-34, 69-72, 82-84
       3    1 H      35-62, 85-98

     ... skip ...
     ------------------------------------------------------------------------
     |                        INNER REGION CHARGE =  0                      |
     ------------------------------------------------------------------------

   normal termination of xtb
```

--------------------------------

### Configure installation prefix

Source: https://xtb-docs.readthedocs.io/en/latest/development.html

Adjust the installation directory before performing the final installation.

```bash
meson configure build --prefix=$HOME/.local
```

--------------------------------

### Example Thermo Calculation

Source: https://xtb-docs.readthedocs.io/en/latest/xtb_thermo.html

Example workflow showing an initial xtb calculation followed by a thermo analysis with specific rotor cutoff and temperature settings.

```bash
xtb benzene.xyz --namespace benzene --ohess
...
xtb thermo --sthr 100 --temp 50,100,150,200,250,300 benzene.xtbopt.xyz benzene.hessian
```

--------------------------------

### Fukui Index Output Example for BF3

Source: https://xtb-docs.readthedocs.io/en/latest/sp.html

Example output showing the Fukui index calculation results for BF3.

```text
Fukui index Calculation
   1    -15.6291014 -0.156291E+02  0.835E+00   13.96       0.0  T
   2    -15.6761217 -0.470203E-01  0.533E+00   13.46       1.0  T
   3    -15.6768113 -0.689578E-03  0.156E+00   13.00       1.0  T
   4    -15.6769156 -0.104364E-03  0.175E-01   12.86       1.0  T
   5    -15.6769184 -0.275858E-05  0.213E-02   12.90       2.3  T
   6    -15.6769197 -0.132996E-05  0.325E-03   12.91      15.4  T
   7    -15.6769197  0.872775E-08  0.253E-03   12.91      19.8  T
   8    -15.6769197 -0.144533E-07  0.264E-05   12.91    1896.8  T
   9    -15.6769197 -0.126121E-11  0.650E-06   12.91    7694.1  T
     SCC iter.                  ...        0 min,  0.001 sec
     gradient                   ...        0 min,  0.000 sec
   1    -14.9103537 -0.149104E+02  0.313E+00    8.30       0.0  T
   2    -14.9107747 -0.421013E-03  0.195E+00    8.21       1.0  T
   3    -14.9108376 -0.628755E-04  0.217E-01    8.29       1.0  T
   4    -14.9108954 -0.578357E-04  0.166E-01    8.21       1.0  T
   5    -14.9003399  0.105555E-01  0.141E+00    8.21       1.0  T
   6    -14.9108133 -0.104734E-01  0.172E-01    8.22       1.0  T
   7    -14.9109267 -0.113342E-03  0.872E-02    8.22       1.0  T
   8    -14.9109654 -0.387429E-04  0.200E-02    8.23       2.5  T
   9    -14.9109672 -0.181816E-05  0.417E-03    8.24      12.0  T
  10    -14.9109673 -0.412949E-07  0.111E-03    8.23      45.1  T
  11    -14.9109673 -0.551257E-08  0.351E-04    8.23     142.6  T
  12    -14.9109673 -0.493735E-09  0.682E-05    8.23     733.6  T
     SCC iter.                  ...        0 min,  0.001 sec
     gradient                   ...        0 min,  0.000 sec

     #       f(+)     f(-)     f(0)    #Fukui indexes
     1 B    -0.300    0.005   -0.148
     2 F    -0.233   -0.335   -0.284
     3 F    -0.233   -0.335   -0.284
     4 F    -0.233   -0.335   -0.284
```

--------------------------------

### QCxMS2 Output Example

Source: https://xtb-docs.readthedocs.io/en/latest/qcxms2_doc/qcxms2_ex.html

Standard output header displayed when running QCxMS2.

```text
     -----------------------------------------------------------
     |                   =====================                   |
     |                   =       QCxMS2      =                   |
     |                   =====================                   |
     |                      J. Gorges                            |
     |                      S. Grimme                            |
     |          Mulliken Center for Theoretical Chemistry        |
     |                    University of Bonn                     |
      -----------------------------------------------------------

   * QCxMS2 version 1.0.0 (24729a4) compiled by 'gorges@joey' on 2025-01-20
   QCxMS2 is free software: you can redistribute it and/or modify it under
   the terms of the GNU Lesser General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   QCxMS2 is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU Lesser General Public License for more details.


 Command line input:
 > qcxms2 in.xyz -T 16
```

--------------------------------

### Install Meson and Ninja via pip

Source: https://xtb-docs.readthedocs.io/en/latest/_sources/development.rst.txt

Use pip to install the required build tools on systems where they are not available via the package manager.

```none
pip install meson ninja [--user]
```

--------------------------------

### ENSO Configuration File Example

Source: https://xtb-docs.readthedocs.io/en/latest/_sources/enso_doc/enso_usage.rst.txt

Example content for the flag.dat configuration file used to define calculation parameters.

```text
FLAGS
nconf: all                                 # all or integer between 0 and total number of conformers
charge: 0                                  # integer
unpaired: 0                                # integer
solvent: chcl3                             # acetone, acetonitrile, chcl3, ch2cl2, dmso, h2o, methanol, thf, toluene, gas 
prog: tm                                   # tm, orca
ancopt: on                                 # on, off
prog_rrho: xtb                             # xtb, prog
gfn_version: gfn2                          # gfn1, gfn2
temperature: 298.15                        # in Kelvin
prog3: tm                                  # tm, orca, prog
prog4: tm                                  # prog, tm, orca
part1: on                                  # on, off
part2: on                                  # on, off
part3: on                                  # on, off
part4: on                                  # on, off
boltzmann: off                             # on, off
backup: off                                # on, off
func: pbeh-3c                              # pbeh-3c, b97-3c, tpss 
func3: pw6b95                              # pw6b95, wb97x, dsd-blyp 
basis3: def2-TZVPP                         #  
couplings: on                              # on, off
funcJ: pbe0                                # tpss, pbe0 
basisJ: default                            #  
shieldings: on                             # on, off
funcS: pbe0                                # tpss, pbe0 
basisS: default                            # 
part1_threshold: 4.0                       # integer or real number
part2_threshold: 2.0                       # integer or real number
sm: dcosmors                               # cosmo, dcosmors, cpcm, smd
smgsolv2: sm                               # sm, cosmors
sm3: dcosmors                              # dcosmors, cosmors, smd
sm4: cosmo                                 # cosmo, cpcm, smd
check: on                                  # on, off
crestcheck: off                            # on, off
maxthreads: 1                              # integer larger than 0
omp: 4                                     # integer larger than 0
reference for 1H: TMS                      # TMS, DSS
reference for 13C: TMS                     # TMS, DSS
1H active: on                              # on, off
13C active: off                            # on, off
19F active: off                            # on, off
31P active: off                            # on, off
resonance frequency: 400                   # integer
end
```

--------------------------------

### XTB Output Log Example

Source: https://xtb-docs.readthedocs.io/en/latest/ptb.html

Example of a standard XTB output log containing bond orders, dipole moments, and quadrupole tensor data.

```text
 ---------------------------------------------------------------------------
     #   Z sym  total        # sym  WBO       # sym  WBO       # sym  WBO
 ---------------------------------------------------------------------------
     1   6 C    3.965 --     6 C    1.445     2 C    1.429     9 H    0.989
     2   6 C    3.977 --     1 C    1.429     3 C    1.429    10 H    0.993
     3   6 C    3.965 --     4 C    1.445     2 C    1.429    11 H    0.989
     4   6 C    3.967 --     3 C    1.445     5 C    1.403     7 H    0.982
     5   6 C    4.006 --     4 C    1.403     6 C    1.403    24 N    1.052
     6   6 C    3.967 --     1 C    1.445     5 C    1.403     8 H    0.982
     7   1 H    1.016 --     4 C    0.982
     8   1 H    1.016 --     6 C    0.982
     9   1 H    1.035 --     1 C    0.989
    10   1 H    1.038 --     2 C    0.993
    11   1 H    1.035 --     3 C    0.989
    12   6 C    3.992 --    13 C    1.441    17 C    1.440    21 H    0.993
    13   6 C    3.994 --    12 C    1.441    14 C    1.441    22 H    0.994
    14   6 C    3.992 --    13 C    1.441    15 C    1.440    23 H    0.993
    15   6 C    3.987 --    14 C    1.440    16 C    1.439    18 H    0.991
    16   6 C    3.980 --    15 C    1.439    17 C    1.439    19 H    0.988
    17   6 C    3.987 --    12 C    1.440    16 C    1.439    20 H    0.991
    18   1 H    1.038 --    15 C    0.991
    19   1 H    1.033 --    16 C    0.988
    20   1 H    1.038 --    17 C    0.991
    21   1 H    1.041 --    12 C    0.993
    22   1 H    1.042 --    13 C    0.994
    23   1 H    1.041 --    14 C    0.993
    24   7 N    4.311 --    26 O    1.621    25 O    1.621     5 C    1.052
    25   8 O    1.880 --    24 N    1.621    26 O    0.198
    26   8 O    1.880 --    24 N    1.621    25 O    0.198
 ---------------------------------------------------------------------------

Topologies differ in total number of bonds
Writing topology from bond orders to xtbtopo.mol

 --------------------------------------
    Molecular dipole moment (a.u.)
    X        Y        Z
 --------------------------------------
   -1.6560  -0.9605   0.0032
 --------------------------------------
    Total dipole moment (a.u. / Debye):
    1.9144   4.8658

 --------------------------------------
    Molecular quadrupole tensor: (a.u.)
         X         Y         Z
    X   -4.6099
    Y  -18.7964    6.5225
    Z  -17.6585  -10.2393   -1.9126
 --------------------------------------
```

--------------------------------

### Input XYZ File Format

Source: https://xtb-docs.readthedocs.io/en/latest/qcxms2_doc/qcxms2_ex.html

Example of the input molecule structure in xyz format.

```text
16
 energy: -19.369243382271 gnorm: 0.000059854204 xtb: 6.7.1 (c3cfd38)
C           -2.29405560010000       -0.27259858260000       -0.04531328360000
C           -0.85954151760000        0.13277118300000        0.03148097580000
H            2.24425572750000        0.53480936730000        1.23713232400000
H            2.96327249650000        0.83035531710000       -0.38177427930000
H            1.31387583970000        1.35087511890000       -0.01066709370000
H           -2.93292965850000        0.59208722380000        0.12637019020000
H           -2.48111111390000       -0.64731393490000       -1.05423159230000
H           -2.52058929890000       -1.07062880960000        0.65758710200000
C            0.10120807380000       -1.03484257470000        0.26200375960000
H            1.40410160480000       -0.72810178930000       -1.43884752540000
O           -0.47850220350000        1.26211030440000       -0.06582215180000
C            1.45928778880000       -0.72962759280000       -0.34614099520000
H            0.16276621020000       -1.12030023870000        1.35329069430000
H           -0.32390361780000       -1.95834270590000       -0.12964936090000
C            2.06708660020000        0.54100991220000        0.16232423460000
H            2.11763590860000       -1.57227915380000       -0.08124961590000
```

--------------------------------

### Define reactant structure start.xyz

Source: https://xtb-docs.readthedocs.io/en/latest/_sources/path.rst.txt

Starting geometry for the Diels-Alder reaction example.

```none
15
    
C   -1.05403119  -0.85921125  -1.07844148
O   -0.74716995  -1.59204846   0.00037929
C    1.91999122   0.31825506  -0.65929558
C   -1.56348463   0.34378897  -0.70923752
C   -1.05432765  -0.85883374   1.07895685
C    1.92016161   0.31774885   0.65905212
C   -1.56373749   0.34366980   0.70888173
H   -0.86626022  -1.30691107  -2.03849048
H    2.21980037  -0.54462844  -1.23619995
H    1.61547946   1.18008308  -1.23636699
H   -1.89753571   1.13638114  -1.35561033
H   -0.86679445  -1.30614725   2.03907198
H    2.21960266  -0.54586684   1.23524723
H    1.61610877   1.17913244   1.23678680
H   -1.89780281   1.13623322   1.35526633
```

--------------------------------

### SCC Iteration Output

Source: https://xtb-docs.readthedocs.io/en/latest/pcem.html

Example of the self-consistent charge iteration output showing the setup and convergence of the xTB Hamiltonian with point charges.

```text
           -------------------------------------------------
          |        Self-Consistent Charge Iterations        |
           -------------------------------------------------

          ...................................................
          :                      SETUP                      :
          :.................................................:
          :  # basis functions                  12          :
          :  # atomic orbitals                  12          :
          :  # shells                            8          :
          :  # electrons                        16          :
          :  max. iterations                   250          :
          :  Hamiltonian                  GFN2-xTB          :
          :  restarted?                      false          :
          :  GBSA solvation                  false          :
          :  PC potential                     true          :
          :  -> # point charges                  6          :
          :  -> sum of PC                0.0000000     e    :
          :  electronic temp.          300.0000000     K    :
          :  accuracy                    1.0000000          :
          :  -> integral cutoff          0.2500000E+02      :
          :  -> integral neglect         0.1000000E-07      :
          :  -> SCF convergence          0.1000000E-05 Eh   :
          :  -> wf. convergence          0.1000000E-03 e    :
          :  Broyden damping             0.4000000          :
          ...................................................

 iter      E             dE          RMSdq      gap      omega  full diag
   1    -10.2141283 -0.102141E+02  0.418E+00   13.25       0.0  T
   2    -10.2169842 -0.285597E-02  0.241E+00   13.15       1.0  T
   3    -10.2175075 -0.523314E-03  0.392E-01   12.35       1.0  T
   4    -10.2176392 -0.131616E-03  0.871E-02   12.57       1.0  T
   5    -10.2176471 -0.790990E-05  0.417E-02   12.50       1.0  T
   6    -10.2176488 -0.172257E-05  0.237E-03   12.52      17.3  T
   7    -10.2176488 -0.524712E-08  0.835E-04   12.52      48.9  T
   8    -10.2176488  0.134836E-09  0.623E-04   12.52      65.5  T

   *** convergence criteria satisfied after 8 iterations ***

         :::::::::::::::::::::::::::::::::::::::::::::::::::::
         ::                     SUMMARY                     ::
         :::::::::::::::::::::::::::::::::::::::::::::::::::::
         :: total energy             -10.155934019173 Eh    ::
         :: gradient norm              0.024959693967 Eh/a0 ::
         :: HOMO-LUMO gap             12.520985724021 eV    ::
         ::.................................................::
         :: SCC energy               -10.217648797540 Eh    ::
         :: -> isotropic ES            0.066792092832 Eh    ::
         :: -> anisotropic ES         -0.002669047466 Eh    ::
         :: -> anisotropic XC         -0.001310421597 Eh    ::
         :: -> dispersion             -0.000808230531 Eh    ::
         :: repulsion energy           0.061714760838 Eh    ::
         :: add. restraining           0.000000000000 Eh    ::
         :::::::::::::::::::::::::::::::::::::::::::::::::::::
```

--------------------------------

### Example Default Input File Header

Source: https://xtb-docs.readthedocs.io/en/latest/_sources/xcontrol.rst.txt

Shows the initial lines of a generated default input file, including command metadata and system state.

```text
$cmd xtb --input default.inp --define --copy coord
$date 2019/03/05 at 08:50:26.651
$chrg 0
$spin 0
...
```

--------------------------------

### Configure and Build with Intel Fortran and MKL

Source: https://xtb-docs.readthedocs.io/en/latest/_sources/development.rst.txt

Set the Intel compilers and configure the build for release mode using MKL as the default backend.

```bash
export FC=ifort CC=icc
meson setup build --buildtype=release
```

```bash
ninja -C build
```

--------------------------------

### Perform a GFN2-xTB calculation in C

Source: https://xtb-docs.readthedocs.io/en/latest/_sources/capi.rst.txt

Example demonstrating the initialization of the environment, calculator, results, and molecular structure objects to obtain the total energy.

```c
#include <stddef.h>

#include "xtb.h"

int main (int argc, char** argv)
{
  double energy = 0.0;
  int    const natoms = 7;
  int    const attyp[7] = {6,6,6,1,1,1,1};
  double const charge = 0.0;
  int    const uhf = 0;
  double const coord[3*7] =
      {0.00000000000000, 0.00000000000000,-1.79755622305860,
       0.00000000000000, 0.00000000000000, 0.95338756106749,
       0.00000000000000, 0.00000000000000, 3.22281255790261,
      -0.96412815539807,-1.66991895015711,-2.53624948351102,
      -0.96412815539807, 1.66991895015711,-2.53624948351102,
       1.92825631079613, 0.00000000000000,-2.53624948351102,
       0.00000000000000, 0.00000000000000, 5.23010455462158};

  /*
   * All objects except for the molecular structure can be
   * constructued without other objects present.
   *
   * The construction of the molecular structure locks the
   * number of atoms, atomic number, total charge, multiplicity
   * and boundary conditions.
  **/
  xtb_TEnvironment env = xtb_newEnvironment();
  xtb_TCalculator calc = xtb_newCalculator();
  xtb_TResults res = xtb_newResults();
  xtb_TMolecule mol = xtb_newMolecule(
      env, &natoms, attyp, coord, &charge, &uhf, NULL, NULL);
  if (xtb_checkEnvironment(env)) {
    xtb_showEnvironment(env, NULL);
    return 1;
  }
```

--------------------------------

### ANMR Output Example

Source: https://xtb-docs.readthedocs.io/en/latest/enso_doc/enso_usage.html

Example output generated by the ANMR program.

```text
       +--------------------------------------+
       |              A N M R                 |
       |             S. Grimme                |
       |      Universitaet Bonn, MCTC         |
       |             1989-2019                |
       |            version 3.5               |
       |     Sat Feb  9 06:41:57 CET 2019     |
       +--------------------------------------+
       Based on a TurboPascal program written
       in 1989 which was translated to F90 in
       2005 and re-activated in 2017.
       Please cite work employing this code as:
       ANMR Ver. 3.5: An automatic, QC based
       coupled NMR spectra simulation program.
       S. Grimme, Universitaet Bonn, 2019
       S. Grimme, C. Bannwarth, S. Dohm, A. Hansen
       J. Pisarek, P. Pracht, J. Seibert, F. Neese
       Angew. Chem. Int. Ed. 2017, 56, 14763-14769.
       DOI:10.1002/anie.201708266


 =============================
    # OMP threads =           1
 =============================
 reading <.anmrrc> for standard data
 Read TM from anmrrc
           1   31.7860000000000       0.000000000000000E+000           1
           6   189.674000000000       0.000000000000000E+000           0
           9   182.570000000000       0.000000000000000E+000           0
          15   291.900000000000       0.000000000000000E+000           0
1H resonance frequency (-mf <real>)    :  400.00
line width             (-lw <real>)    :    1.00
number of all conformers               :25
remove J couplings to OH groups        : T
maximum spin system size in a fragment :14
fragmentation type (0=none,1=at,2=mol) : 2
chemical shift scalings a,b            :    1.00    0.00
spin-spin coupling scal factor         :    1.07
plot offset                            :    0.00
Active nuclei                          :H
...
SKIPPING A LOT OF OUTPUT
...
            === FRAGMENTED SYSTEM ===
 ====================================================
      solving (J/sigma) averaged spin Hamiltonian
 ====================================================
          spinsystem            1  with            9  spins
          1024 product functions    12 Mt blocks, largest is    210
  1(   1)  2(   9)  3(  37)  4(  93)  5( 162)  6( 210)  7( 210)  8( 162)  9(  93) 10(  37) 11(   9) 12(   1)
first maxtrix multiply,  sparsity in %    99.536 ...
second maxtrix multiply, sparsity in %    94.781 ...
           512 product functions    10 Mt blocks, largest is    126
  1(   1)  2(   9)  3(  36)  4(  84)  5( 126)  6( 126)  7(  84)  8(  36)  9(   9) 10(   1)
first maxtrix multiply,  sparsity in %    99.121 ...
second maxtrix multiply, sparsity in %    91.919 ...
 done.
       12436  non-zero transitions.
 spectrum on <anmr.dat>
 Range (delta in ppm)   0.437872924804687        7.03675048828125
 Range (delta in Hz)     175.149169921875        2814.70019531250
 Min/max Int.      )    4.171584807901128E-003
 computing spectrum ...
 done.
 writing output file ...
 done.
 All done.
```

--------------------------------

### Initialize xTB from parameter file

Source: https://xtb-docs.readthedocs.io/en/latest/_posts/2021/dftbplus-version-21.2.html

Configure the xTB Hamiltonian using a specific parameter file path instead of a predefined method name.

```hsd
# ...
Hamiltonian = xTB {
  ParameterFile = "gfn2-xtb.toml"
  # ...
}
```

--------------------------------

### Benzene-Nitrobenzene Example

Source: https://xtb-docs.readthedocs.io/en/latest/_sources/dipro.rst.txt

Example command and coordinate file for a cofacial NCI complex.

```none
> xtb coord.xyz --dipro --gfn 1
```

```none
26

C         -1.20618        0.69599        1.75211
C         -1.20379       -0.70017        1.75215
C          0.00616       -1.39690        1.75210
C          1.21824       -0.70002        1.75171
C          1.23033        0.70989        1.75117
C          0.00125        1.40067        1.75172
H          2.14504       -1.25925        1.74975
H         -0.02278        2.48280        1.74976
H         -2.14520        1.23405        1.75041
H         -2.14028       -1.24255        1.75044
H          0.00554       -2.47919        1.75040
C         -1.21072        0.69984       -1.75114
C         -1.21074       -0.69902       -1.75149
C          0.00072       -1.39843       -1.75114
C          1.21220       -0.69897       -1.75037
C          1.21222        0.69988       -1.74995
C          0.00077        1.39929       -1.75036
H          2.14941       -1.24008       -1.74839
H          2.14945        1.24099       -1.74755
H          0.00077        2.48148       -1.74837
H         -2.14799        1.24091       -1.74971
H         -2.14800       -1.24014       -1.75028
```

--------------------------------

### Access xTB Help

Source: https://xtb-docs.readthedocs.io/en/latest/_sources/setup.rst.txt

Display the in-program help documentation.

```bash
> xtb --help
```

--------------------------------

### Build and Install SCINE XTB Wrapper

Source: https://xtb-docs.readthedocs.io/en/latest/_sources/community/scine.rst.txt

Standard build process using CMake to compile the wrapper and generate the module file.

```bash
mkdir build
cd build
cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=<desired path> ..
make -j<number of cores to use>
make install
```

--------------------------------

### Installing Mamba

Source: https://xtb-docs.readthedocs.io/en/latest/_sources/qcxms_doc/qcxms_setup.rst.txt

Command to install the mamba package manager as a faster alternative to conda.

```none
conda install mamba -c conda-forge
```

--------------------------------

### Configure path.inp settings

Source: https://xtb-docs.readthedocs.io/en/latest/_sources/path.rst.txt

Recommended starting parameters for the reaction path finder.

```none
$path
   nrun=1
   npoint=25
   anopt=10
   kpush=0.003
   kpull=-0.015
   ppull=0.05
   alp=1.2
$end
```

--------------------------------

### Installing QCxMS via Conda

Source: https://xtb-docs.readthedocs.io/en/latest/_sources/qcxms_doc/qcxms_setup.rst.txt

Command to install the qcxms package from the conda-forge channel.

```none
conda install qcxms
```

--------------------------------

### Example coordinate file

Source: https://xtb-docs.readthedocs.io/en/latest/_sources/ptb.rst.txt

Sample input coordinate file (coord.xyz) for a molecular structure.

```none
12

C         -1.21072        0.69984       -1.75114
C         -1.21074       -0.69902       -1.75149
C          0.00072       -1.39843       -1.75114
C          1.21220       -0.69897       -1.75037
C          1.21222        0.69988       -1.74995
C          0.00077        1.39929       -1.75036
H          2.14941       -1.24008       -1.74839
H          2.14945        1.24099       -1.74755
H          0.00077        2.48148       -1.74837
H         -2.14799        1.24091       -1.74971
H         -2.14800       -1.24014       -1.75028
H          0.00066       -2.48066       -1.74972
```

--------------------------------

### Install CENSO via pip

Source: https://xtb-docs.readthedocs.io/en/latest/_sources/CENSO_docs/censo.rst.txt

Commands to install the CENSO package in the current environment.

```sh
pip install .
```

```sh
pip install censo
```

--------------------------------

### View ANCopt Setup Configuration

Source: https://xtb-docs.readthedocs.io/en/latest/optimization.html

Summary of the optimization parameters and convergence criteria used during the run.

```text
               ...................................................
               :                      SETUP                      :
               :.................................................:
               :   optimization level             tight          :
               :   max. optcycles                    50          :
               :   ANC micro-cycles                  20          :
               :   degrees of freedom                24          :
               :.................................................:
               :   RF solver                      spevx          :
               :   input Hessian                  false          :
               :   write xtbopt.log                true          :
               :   linear?                        false          :
               :   energy convergence         0.1000000E-05 Eh   :
               :   grad. convergence          0.8000000E-03 Eh/α :
               :   maximium RF displ.         1.0000000          :
               :   Hlow (freq-cutoff)         0.2000000E-01      :
               :   Hmax (freq-cutoff)         5.0000000          :
               :   S6 in model hess.         20.0000000          :
               ...................................................
```
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