Molcas Forum

Yongyi

Member

Registered: 2023-04-03

Posts: 1

Questions Regarding the QMSTAT module

Dear All:

I am trying to add solvation, semiempirical corrections on dispersion with damping on my QM system. I cannot fully understand how the QMSTAT should be used after I read the manual. Here are a few questions:

1. The manual used water as the MM solvent, and call it in the input sample. Is other solvents available in this module (e.g. Benzene)?

2. The ATCEchpol keyword seems to allow a detail definition of the solvent. If I were to use discrete solvent other than water in QMSTAT, do I need to start here and define all related parameters? (This question is out of curiosity, since "creating a new solvent" may be too complex for me.)

3. I want to use Grimme's dispersion (DFT-D4, particularly), and the parameters in "dampling dispersion" in the manual looks quite different from those from Grimme's publications. Does that mean I cannot use them even I am willing to enter the parameters on my own, unless I modify the codes?

4. Suppose I want to add solvation, and add dispersion and damping corrections only on the QM region only, can I do the following:
a. Use PCM to treat solvation. This means to use QMSTAT and PCM (the PCM is in other modules) together
b. Use the following command to disable MM water:
  Simulation
  Temperature = 0; Surface = 0; Translation = 0; Rotation = 0;
  End of Simulation
  Steps = 1 1; Run = QMEQ;
  Configuration
  Add = 0 *NO WATER! The reaction field is handled by PCM.
  End of Configuration
c. Add damping for QM region with:
  Dispersion
  -6.64838476  -5.22591434  -4.32517889 -4.58504467     * Water Hydrogen.
  -.34146881   -0.21833165  -0.22092206 -0.21923063     * Water Oxygen.
* Valence Charge and Diagonal terms in the Quadrupole tensors for QM atoms*
  End Damping

I will be very grateful if you can answer (one of) them.

Regards,
Yongyi

Last edited by Yongyi (2023-04-03 15:24:31)