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Cubic response by mp2

Posted: 26 Apr 2014, 02:25
by kaushikhatua
Can anybody suggest input hints for cubic response calculation by mp2 method. I have done some cubic response run in hf and different dft functional and ccsd as well. Any help will be appreciated.

Re: Cubic response by mp2

Posted: 26 Apr 2014, 07:28
by janus
I would not go down that way as the MP2 response function does not have a pole structure that is consistent with the one of the exact linear response function, as pointed out in Ref. [1]. This paper also suggests to use the CC2 model instead if you're after an 'second-order' model. This model - unlike MP2 - gives response functions with a pole structure consistent with exact theory. You could also consider SOPPA, but here you'll only be able to go to linear response, not cubic.

Cheers,
Janus

Ref. [1]: Christiansen, Jørgensen, and Hättig, IJQC, 68, 1-52 (1998)