Author Topic: point charges in a HF-3c calculation  (Read 2376 times)

makochman1

  • Newbie
  • *
  • Posts: 3
  • Karma: +0/-0
point charges in a HF-3c calculation
« on: July 27, 2021, 04:46:42 PM »
Dear Users and Developers of Turbomole,

I ran into a problem when trying to set up a HF-3c calculation with external point charges in Turbomole 7.5.0. (The idea was to use the fast HF-3c method in QM/MM molecular dynamics simulations.) If I understand correctly, the subprogram grad is including the point charges in some of the corrections specific to HF-3c.

In order to illustrate this issue, I uploaded some example input files to google drive:

https://drive.google.com/file/d/1vNODwOjyDv9khtdtX5T4PhKiwuwCpm6m/view?usp=sharing

They represent a small organic molecule. There are two point charges of +1 and -1 positioned far from the molecule, and 2 bohr from one another. The gradient acting on the point charges should be:

 -0.25  0.00  0.00
  0.25  0.00  0.00
 
A conventional HF/cc-pVDZ calculation (in directory 0_DMABN_with_point_charges_HF_ccpVDZ) gets that right, but the HF-3c (1_DMABN_with_point_charges_HF_3c) calculation does not. (Of course it's entirely possible I am misunderstanding how a HF-3c calculation should be set up.) Is there a way to get the expected behaviour with HF-3c?

With best regards,

Michal Kochman