From JKONG # - at - # chem1.chem.dal.ca Wed Dec 7 12:18:06 1994 Received: from Snoopy.UCIS.Dal.CA for JKONG[ AT ]chem1.chem.dal.ca by www.ccl.net (8.6.9/930601.1506) id MAA23642; Wed, 7 Dec 1994 12:04:41 -0500 From: Received: from chem1.chem.dal.ca (CHEM1.Chem.Dal.Ca [129.173.17.47]) by Snoopy.UCIS.Dal.CA (8.6.8.1/8.6.6) with SMTP id NAA11492 for ; Wed, 7 Dec 1994 13:04:38 -0400 Received: from CHEM1/MERCURYQUEUE by chem1.chem.dal.ca (Mercury 1.13); Wed, 7 Dec 94 13:04:38 -0400 Received: from MERCURYQUEUE by CHEM1 (Mercury 1.13); Wed, 7 Dec 94 13:04:15 -0400 To: chemistry -8 at 8- ccl.net Date: Wed, 7 Dec 1994 13:04:09 AST Subject: Help needed with SCF convergence Priority: normal X-mailer: Pegasus Mail v3.1 (R1) Message-ID: <19D1CED0E58 {*at*} chem1.chem.dal.ca> Dear netters, I am searching the energy surface of a triatomic molecule (doublet) with ROHF method and got convergence problem whenever I try to bend the molecule. The scf procedure goes okay until the total energy difference between two consecutive iteration steps is at the 7th decimal place. Then the difference remains almost constant and the iteration goes on forever. I tried vshift option with g92 but it didn't work. G92 manual says scf=qc does not apply to ROHF. The program I am using now is meldf. With meldf, sometimes it works, sometimes it doesn't, even if the guess is from a previous run with a smaller angle. Can anyone give me advices? Thanks! Jing