integration grid in Hessian/frequencies task
Clicked A Few Times
6:53:35 AM PDT - Mon, Jul 30th 2018
Hi

Does the calculation of the Hessian uses exactly the same integration grid as specified in the DFT directive of a preliminary geometry optimization task?

For instance, consider the following input:

DFT
...
grid xfine
END
TASK dft optimize
TASK dft frequencies

Will NWChem use the xfine grid for the calculation of the Hessian?

I'm asking because there is indeed other software that silently runs CPHF routines using a grid that is not as fine as in calculation of energy and gradient. And sometimes this approximation results in loss of accuracy (see this paper ).

Thanks!

Marco

Forum Vet
9:50:48 AM PDT - Mon, Jul 30th 2018
NWChem uses the same grid in the Hessian as previously defined in the input. However, several computational parameters are tightened up (e.g. Schwarz screening for 2-electron integrals, screening on electron density for XC evaluation).


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