Upgrade to DFT-D4 in QChem 6.4

Questions
#1

Hi, all,

Would it be possible to clarify what specifically was improved about the D4 dispersion in the recent version upgrade?

Can energies from QChem 6.3’s implementation be used interchangeably with those in 6.4?

I use a version that is implemented as a module on HPC infrastructure, and was recently swapped to 6.4 while I wasn’t looking. I can’t unilaterally downgrade to keep everything the same.

Thanks!

#2

Based on the change logs, it looks like we went from D4 v. 2.5.0 to v. 3.7.0 (Grimme group’s numbering scheme) between Q-Chem versions 6.3 and 6.3.1. So far as what those changes entail you will need to consult the Grimme group’s documentation. The short description seems to be “new parameters for functionals like r2SCAN, along with fixes for some compiler bugs related to Intel’s OneAPI”.

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