ASH: a computational chemistry environment

ASH is a Python-based computational chemistry and QM/MM environment, primarily for molecular calculations in the gas phase, explicit solution, crystal or protein environment. Can do single-point calculations, geometry optimizations, surface scans, molecular dynamics, numerical frequencies etc. using a MM, QM or QM/MM Hamiltonian. Interfaces to popular QM codes: ORCA, xTB, Psi4, PySCF, Dalton, CFour, MRCC.

While ASH is ready to be used in computational chemistry research, it is a young project and there will probably be some issues and bugs to be discovered if you start using it.

In case of problems: Please open an issue on Github and I will try to fix any problems as soon as possible.

Documentation:

https://ash.readthedocs.io/en/latest

Development:

ASH welcomes any contributions.

Ongoing priorities:

Improve documentation of code, write docstrings.
Write unit tests
Rewrite silly old code.
Reduce code redundancy.
Improve program documentation

Example:

from ash import *

coords="""
H 0.0 0.0 0.0
F 0.0 0.0 1.0
"""
#Create fragment from multi-line string
HF_frag=Fragment(coordsstring=coords, charge=0, mult=1)

#Alternative: Create fragment from XYZ-file
HF_frag=Fragment(xyzfile="hf.xyz", charge=0, mult=1)

#Define ORCA theory settings strings
input="! r2SCAN def2-SVP def2/J tightscf"
blocks="%scf maxiter 200 end"
#Define ORCA theory object
ORCAcalc = ORCATheory(orcasimpleinput=input, orcablocks=blocks)

#Call optimizer with ORCAtheory object and fragment as input
geomeTRICOptimizer(theory=ORCAcalc,fragment=HF_frag)

0xBytefuzz/ash

ASH: a computational chemistry environment