qcinput 0.1.0

Generate quantum chemistry input files from molecular structures

qcinput

qcinput is a CLI tool that reads an xyz geometry, loads task type and keywords from TOML, and writes an ORCA or Gaussian input file.

Install With pip

python -m pip install .

For development:

python -m pip install -e .

Run With Nix

nix develop -c qcinput

Or run directly from the flake package:

nix run .

Usage

qcinput generate <path/to/structure.xyz> [-c|--config <path/to/qcinput.toml>] [-o output.inp]

Compatibility shorthand (same behavior):

qcinput <path/to/structure.xyz> [-c|--config <path/to/qcinput.toml>] [-o output.inp]

First-time setup:

qcinput init-config

Default config path:

./qcinput.toml

You can override this with:

QCINPUT_CONFIG=/path/to/config.toml qcinput water.xyz

Example:

qcinput water.xyz -c qcinput.toml -o water_opt.inp

When qcinput.engine = "gaussian", default output suffix is .gjf.

Config Format (TOML)

We use TOML because it is readable for humans, easy to version control, and strongly structured.

[qcinput]
engine = "orca" # or "gaussian"
kind = "int" # int | ts | sp

[molecule]
charge = 0
multiplicity = 1

[orca]
nprocs = 8
maxcore = 4000
base_keywords = ["r2scan-3c", "D4", "def2-mTZVPP"]

[orca.task.int]
keywords = ["Opt", "Freq"]

[orca.task.ts]
keywords = ["OptTS", "Freq"]

[orca.task.sp]
keywords = ["SP"]

[gaussian]
nprocshared = 8
mem = "8GB"
method_basis = "B3LYP/def2TZVP"

[gaussian.task.int]
route = ["Opt", "Freq"]

[gaussian.task.ts]
route = ["OptTS", "Freq"]

[gaussian.task.sp]
route = ["SP"]

Output Snippet

# Generated by qcinput from water.xyz
! Opt Freq r2scan-3c D4 def2-mTZVPP
%pal nprocs 8 end
%maxcore 4000
* xyz 0 1
O 0.000000 0.000000 0.000000
H 0.757000 0.586000 0.000000
H -0.757000 0.586000 0.000000
*