tag:blogger.com,1999:blog-329801097007474097.post6779653173422607068..comments2019-11-11T12:35:20.224+01:00Comments on Computational Chemistry Highlights: The minimum parameterization of the wave function for the many-body electronic Schrödinger equation. I. Theory and ansatzComputational Chemistry Highlightshttp://www.blogger.com/profile/12737582958414627004noreply@blogger.comBlogger2125tag:blogger.com,1999:blog-329801097007474097.post-16539602814559308352019-11-05T18:46:41.444+01:002019-11-05T18:46:41.444+01:00The excerpt is trivial. The 2-RDM is parameterized...The excerpt is trivial. The 2-RDM is parameterized by $m*(m+1)/2$ variables. But parameterization of the 2-RDM is not the same as computational complexity of the solution. Or in other words, the computational complexity is not affected by this argument and remains exponential in the number of one-electron basis functions.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-329801097007474097.post-56234782492587722972019-11-03T12:55:16.959+01:002019-11-03T12:55:16.959+01:00I have some doubts. m(m−1)/2 is O(N^2), so way che...I have some doubts. m(m−1)/2 is O(N^2), so way cheaper than CCSD, or even just HF. I have difficulty believing FCI can be so cheap. Also, I think there is a conjecture that a method cannot be variational and size consistent at the same time without being FCI (or equivalent). <br />With that said, geminals have done some wonderful things for basis set convergence, F12 methods are usually great. Anonymousnoreply@blogger.com