Interface xtb

Interface to the XTB program (github.com/grimme-lab/xtb, open source).

For now, the interface is ony very simple, implementing single-point and gradient calculations with GFN-xTB and GFN2-xTB methods, optionally with the GB solvent.

Warning

There had been various changes in the input and output over the history of xtb. The interface has been tested to be compatible with version 6.2.2.

Methods and capabilities

The interface implements following methods (specified by keyword 'method'):

• gfn-xtb - supports calculation of energy, gradient, atomic_charges
• gfn2-xtb - supports calculation of energy, gradient, atomic_charges
• gfn-ff - supports calculation of energy

The interface implements following solvent models (keyword 'solvent_model'):

• gbm
• alpb
• cosmo
• cpcmx

The interface implements following atomic charge types (keyword 'atomic_charges'):

• mulliken - Mulliken charges

Keywords used

Keywords specific for this interface:

• xtb_home_dir
• xtb_options

Other keywords used by this interface:

• charge
• existing_calc_dir
• job_cleanup
• method
• multiplicity
• parallel
• solvent_model
• solvent_name

Examples

The following examples, along with all other files needed to run them, can be found in the directory cuby4/interfaces/xtb/examples

#===============================================================================
# XTB example 1: energy calculation, configuration
#===============================================================================

# Single-point energy calculation
job: energy
interface: xtb
method: gfn2-xtb

# Water molecule, geometry taken from Cuby's internal database
geometry: A24:water
charge: 0

#-------------------------------------------------------------------------------
# Interface configuration
#-------------------------------------------------------------------------------
# Path to the xtb installation direcory (it contains the bin subdirectory where
# the xtb executable is located, and all the other files).
# This configuration can be added to the global confing.

xtb_home_dir: /home/rezac/bin/xtb/xtb/install
# Provide the actual path on your system here