Molecular Moments and Polarizabilities Calculator

Overview

The Python code is designed for calculating higher-order moments and polarizabilities of small molecules. It is a versatile tool that provides insights into the molecular properties essential for understanding electronic structure and molecular interactions. The moments and polarizabilites so calculated are used as the parameter sets for the SCME code.

Features

Moments Calculation

• Dipole Moment
• Quadrupole Moment
• Octapole Moment
• Hexadecapole Moment

Polarizabilities Calculation

• Dipole-Dipole Polarizability
• Dipole-Quadrupole Polarizability
• Quadrupole-Quadrupole Polarizability

How to Use

Running the code [with PYSCF]

conda create --name cpol-pyscf
conda activate cpol-pyscf
pip3 install cpol-pyscf

copy the following H2O molecule geometry in a molecule.xyz file

3
Properties=species:S:1:pos:R:3 pbc="F F F"
O       -0.00000000       0.00000000       0.06664447
H        0.76804750       0.00000000      -0.52889132
H       -0.76804750       0.00000000      -0.52889132

And run the following script to test out the implementation with pyscf

from pyscf import gto
from ase.io import read
from cpol_pyscf import Pols
import numpy as np
from ase.visualize import view
from ase.units import Bohr, Ha


mol = gto.Mole()
molecule = read("molecule.xyz")
mol.atom = "molecule.xyz" 
mol.basis = "augccpvqz"
mol.build()


field_strength_F = 0.00486/Ha*Bohr


pols = Pols(molecule,mol, irrep=False, field_strength_F=field_strength_F)

print("dd polarizability")
print(pols.calc_dd_pol())
print("dq polarizability")
print(pols.calc_dq_pol())
print("qq polarizability")
print(pols.calc_qq_pol())