CCL:G: eliminate Spin Contamination for CCSD and MP2 in Gaussian



 Sent to CCL by: Decai Yu [decaiyu23]![yahoo.com]
 Dave,
 Thanks.
 But how about CCSD?
 Are there any way to get CCSD energies without spin contamination?
 Decai
 --- On Sat, 1/8/11, Close, David M. CLOSEDa/mail.etsu.edu
 <owner-chemistry^^ccl.net> wrote:
 > From: Close, David M. CLOSEDa/mail.etsu.edu
 <owner-chemistry^^ccl.net>
 > Subject: CCL:G: eliminate Spin Contamination for CCSD and MP2 in Gaussian
 > To: "Yu, Decai " <decaiyu23^^yahoo.com>
 > Date: Saturday, January 8, 2011, 9:56 AM
 >
 > Sent to CCL by: "Close, David M." [CLOSED-x-mail.etsu.edu]
 > Yu:
 >   In the output there is the normal MP2 energy and
 > then a PMP2 energy, followed by three values of S2.
 > The first value of S2 is greater than 1?  That's from
 > the normal MP2 run.  But the next value of S2 comes
 > from the projected MP2 run, and this should be somewhat
 > closer to 0.75.  Is it?
 >   Regards, Dave Close
 >
 > -----Original Message-----
 > > From: owner-chemistry+closed==etsu.edu^_^ccl.net
 > [mailto:owner-chemistry+closed==etsu.edu^_^ccl.net] On
 > Behalf Of Decai Yu decaiyu23:-:yahoo.com
 > Sent: Friday, January 07, 2011 6:44 PM
 > To: Close, David M.
 > Subject: CCL:G: eliminate Spin Contamination for CCSD and
 > MP2 in Gaussian
 >
 >
 > Sent to CCL by: Decai Yu [decaiyu23,yahoo.com]
 > Dear All,
 >
 >  I have encountered significant spin-contamination with
 > MP2
 >  and CCSD using Gaussian 09.
 >  Can anyone comment on how to eliminate the spin
 >  contamination using Gaussian?
 >
 >  Your help is appreciated.
 >
 >  Regards,
 >
 >  Decai Yuhttp://www.ccl.net/cgi-bin/ccl/send_ccl_messagehttp-:-//www.ccl.net/chemistry/sub_unsub.shtmlhttp-:-//www.ccl.net/spammers.txt
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