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<DIV><FONT color=#000000 size=3>Dear Gerald and Kirk,</FONT></DIV>
<DIV> </DIV>
<DIV>Many thanks for your reply. I finally use the procedure
hf/multi/hf(maxit=1)/uccsd-f12(orbital,ignore_error), which works fine now.
I'm also grateful for Gerald's alert about the ccsd energies with non-rhf
orbitals. I would like to do more test to check if the ccsd energies with this
strategy are correct.</DIV>
<DIV> </DIV>
<DIV>Best, Bin.</DIV>
<DIV align=left><FONT color=#c0c0c0 size=2
face=Verdana>2011-08-10</FONT></DIV><FONT size=2 face=Verdana>
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<DIV><FONT color=#c0c0c0 size=2 face=Verdana><SPAN
id=_FlashSignName>binjiang.nju</SPAN></FONT></DIV></FONT>
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</DIV>
<DIV>发件人: Gerald Knizia <knizia@theochem.uni-stuttgart.de></DIV>
<DIV>发送时间: 2011-08-11 05:38</DIV>
<DIV>主 题: Re: [molpro-user] UCCSD-F12 with CASSCF orbitals</DIV>
<DIV>收件人: "binjiang.nju" <binjiang.nju@gmail.com></DIV>
<DIV>抄 送: molpro-user <molpro-user@molpro.net></DIV>
<DIV> </DIV>
<DIV> </DIV>
<DIV><BR><BR></DIV>
<DIV>binjiang.nju wrote: </DIV>
<DIV>> I am trying to do a uccsd(t) calculation with CASSCF orbitals in </DIV>
<DIV>> Molpro.2010.1, it will be useful when two quasi-degenerate states </DIV>
<DIV>> exist and sometimes improve the convergence, comparing to the </DIV>
<DIV>> uccsd(t)/hf strategy. </DIV>
<DIV>> </DIV>
<DIV>> It works fine when I use only normal uccsd(t) option, but it fails </DIV>
<DIV>> when I use uccsd(t)-f12 option. I have tried to change the basis set, </DIV>
<DIV>> active space, as well as the type of CASSCF orbitals (Natural, </DIV>
<DIV>> Canonical), all of these do not help. Then I find some information for </DIV>
<DIV>> such problem, but still no suitalbe answer. </DIV>
<DIV>> </DIV>
<DIV>> Gerald Knizia has mentioned that the F12 methods do request RHF </DIV>
<DIV>> reference functions, but he would try to fix this. (I cite his words </DIV>
<DIV>> in the following, hopefully he would not mind) </DIV>
<DIV> </DIV>
<DIV>I have semi-fixed this in the current development version (i.e., it is </DIV>
<DIV>there possible to use such orbitals now, but it requires some persuation </DIV>
<DIV>with rhf,maxit=1). However, this turned out to be more complicated than </DIV>
<DIV>anticipated, which is why I did not backport the changes to the </DIV>
<DIV>production version. In the current production version both CCSD-F12 </DIV>
<DIV>programs will give (different) wrong energies when used with non-HF </DIV>
<DIV>orbitals. I would prefer to leave this issue open until the next Molpro </DIV>
<DIV>production version (i.e., the one from the current development version, </DIV>
<DIV>where this will work automatically), unless there is very strong </DIV>
<DIV>interest in having this feature available. </DIV>
<DIV>-- </DIV>
<DIV>Gerald Knizia </DIV></DIV></STATIONERY></BODY></HTML>