I abandoned the use of M11-L and instead turned to B2PLYP for my molecule in my previous question, as M11-L seemed in fact to be very poor for my application. Since B2PLYP contains MP2, I looked up the NWChem manual to see if it supports RI-MP2 approximations. The manual did say that it supported RI-MP2, with explicit syntax rules on the fitting basis, but said nothing on RI-DH, let alone where to put the fitting bases in the code.

My question is now clear- does NWChem support RI approximations for the MP2 part of double hybrids, and, if it does, where does one put the fitting basis line in? Q-Chem seems to have the answers to both but I cannot use commercial packages outside of the WebMO demo server.

  • $\begingroup$ +1 but is there any reason why you're asking specifically about NWChem? It seems that what you wanted to do didn't work in Q-Chem and you're looking for a non-commercial alternative, but NWChem is not the only non-commercial electronic structure software. $\endgroup$ Oct 13, 2022 at 14:36
  • $\begingroup$ I prefer to visualise it on WebMO. $\endgroup$ Oct 18, 2022 at 9:23
  • $\begingroup$ The WebMO website says that it supports: "Gamess, Gaussian, MolPro, Mopac, NWChem, Orca, PQS, PSI, Q-Chem, TeraChem, Tinker, Quantum Expresso, and VASP". Included in that list is Orca, which is free, and can do RI-MP2 (as listed in the URL at the end of my second paragraph here). $\endgroup$ Oct 18, 2022 at 9:33
  • $\begingroup$ Didn't know ORCA was free $\endgroup$ Oct 18, 2022 at 11:29
  • 1
    $\begingroup$ I'm not doing this work as an affiliate (currenrly majoring in something else) $\endgroup$ Oct 18, 2022 at 11:30


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