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

 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