DFT First order hyperpolarizability (beta)

johal345 · May 16, 2025, 11:40am

Hi,

In my research group were interested in using Psi4 more for its portability in our workflows but a current bottleneck is not being able to use DFT to calculate the first order hyperpolarizability with DFT akin to gaussian’s Polar key word. Namely using B3LYP or PBE0 with the 6-311G** functional.

I’ve came across this page but believe it only works with coupled-cluster methods/ not entire sure how to perform the calculation in psi4 if it could use DFT:

github.com/psi4/psi4numpy

Response-Theory/Self-Consistent-Field/beta.py

master

"""
A reference implementation to compute the first dipole
hyperpolarizability $\beta$ from a restricted HF reference using the
$2n+1$ rule from perturbation theory.

References:
- Equations taken from [Karna:1991:487]
"""

__authors__   =  "Eric J. Berquist"
__credits__   = ["Eric J. Berquist"]

__copyright__ = "(c) 2014-2018, The Psi4NumPy Developers"
__license__   = "BSD-3-Clause"
__date__      = "2017-08-26"

from itertools import permutations, product

import numpy as np
np.set_printoptions(precision=5, linewidth=200, suppress=True)

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Could you please let me know if the above is usable/ if not any suggestions on adapting it if possible or if there is interest in implementing this more generally in psi4.

Thanks,
Jay