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Re^2: RHF vs ROHF in CPU TIME?

Siddheshwar Chopra

Dear Pavlo,
Thank you for the response. Actually I need to study the neutral molecules, but some have odd number of electrons. I need to study only singlet state. One way I understood is to add a charge, but I can't do that as I need to study the neutral molecules. Please help me understand how to go about it?


On Tue May 6 '14 10:12pm, Pavlo Solntsev wrote
>If your ground state is a closed-shell singlet, why do you need ROHF? If your ground state is not a singlet why do you need RHF?

>I would recommend you to use RHF and UHF. At least it may be useful in case of spin-contamination.

>On Tue May 6 '14 10:04am, Siddheshwar Chopra wrote
>>Dear Firefly Users,
>>Could anyone point out the differences between the RHF and ROHF on the basis of CPU times? I read on some other forum that both of these time scale by N^4. But I need to know say for all the parameters left same, how much do they differ in CPU time? I wish to study the neutral molecules using RHF and ROHF (with same parameters) both. Can I compare their computational results: HOMO-LUMO etc. properties?


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