Units for Nx3 grid in ESP calculation

mdpoleto · July 14, 2024, 3:15pm

Hi there!

I am basing myself on the following example to calculate the ESP over a grid of Nx3 points.

My question is: what are the units of the values provided in the grid points? The code is not clear if those grid points are spaced out in Angstrom or Bohr-radius.

# Number of points to evaluate the ESP on per dimension (reference values below were generated with 5)
numpoints_per_dim = 5
points = np.array([ [float(x),float(y),float(z) ] for x in range(0,numpoints_per_dim) for y in range(0,numpoints_per_dim) for z in range(0,numpoints_per_dim) ])
psi4_matrix = p4c.Matrix.from_array(points)

Full example here:

github.com

psi4/psi4/blob/master/samples/python/mints14/input.py

#! Check for correctness of ESP values. The ESP values are calculated using one or four threads
#! The one thread values are checked against the four thread values. The one thread values are 
#! also checked against the reference values (1 thread values computed, when generating this test).
#! Caution: The reference values are not obtained using an actual physical reference, but rather
#! generated by Psi4 at one point in time.

import psi4
import psi4.core as p4c
import numpy as np

psi4.set_output_file("output.dat", False)

#H2O with minimal basis
h2o = psi4.geometry("""
O
H 1 0.96
H 1 0.96 2 104.5
""")

psi4.set_options({"d_convergence": 1e-10})

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Any help is very much appreciated!

jmisiewicz · July 15, 2024, 1:22pm

Grid points need to be given in input units.

For the example you posted, that means angstroms.

mdpoleto · July 15, 2024, 1:27pm

Excellent! Thank you so much @jmisiewicz !

system · September 13, 2024, 1:28pm

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