Questions tagged [gamess]

Questions related to the GAMESS(US) or GAMESS(UK) software.

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13
votes
2answers
329 views

How to get potential energy surface from GAMESS?

I'm trying to learn GAMESS and performing a simple PES scan of oxygen molecule. After the completion of the calculations I get a .log file with lots of sections like that: ...
9
votes
3answers
821 views

Which software is good with generally contracted basis sets?

Recently, I learnt that basis sets can be contracted as segmented (like def2 or 6-31G) or general (like cc-PVTZ, or ANO). The general contraction allows all the primitives to appear in all shells, ...
8
votes
1answer
77 views

Excited states using ORMAS flag in GAMESS

I am trying to calculate the excited states using single reference CISD on $\ce{CH3OH},$ using ORMAS' CI-X option in GAMESS. As a test example I am using the $\ce{CH3OH}$ that has 2 core, 7 occ. ...
10
votes
1answer
136 views

What are the trade-offs setting DIRSCF to either .TRUE. or .FALSE. (the default) in GAMESS (US)?

The first software I used to run calculations was Gaussian09. When submitting a input, I used to see a pattern of resource usage where the allocated CPU quickly maxed out, remaining high most of the ...
7
votes
1answer
101 views

Computing analytic derivatives of molecular Hamiltonians obtained from solving Hartree-Fock equations

I'm currently working on a quantum chemistry project, I am dealing with a second-quantized electronic Hamiltonian (corresponding to some molecule), written in terms of fermionic creation and ...