From owner-chemistry@ccl.net Sun Aug 31 13:19:01 2008 From: "errol lewars elewars-*-trentu.ca" To: CCL Subject: CCL: Easy convergence of Diffuse functions Message-Id: <-37686-080831123523-29727-XQgbHFkI4CAcusvWbDmiOg|,|server.ccl.net> X-Original-From: errol lewars Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=ISO-8859-1; format=flowed Date: Sun, 31 Aug 2008 12:35:13 -0400 MIME-Version: 1.0 Sent to CCL by: errol lewars [elewars%trentu.ca] 2008 Aug 31 Convergence problems with diffuse functions is a well-known phenomenon. You could try getting a wavefunction with, say, the 6-31G* basis then using that wavefunction as an initial guess for a 6-31+G* job. The keyword for taking the previous wavefunction as your guess depends on your program. E. Lewars === Mr Shabbir shabbir!=!nenu.edu.cn wrote: >Sent to CCL by: "Mr Shabbir" [shabbir]^[nenu.edu.cn] >Dear all >I want to share some thing about optimization. I optimized several systems with 6-31G* basis set but when I use diffuse function (+) the same previously optimized system at (6-31G*) fails to converge by using diffuse function. How to treat the diffuse function especially in optimization? Is there any special keyword or way that can make the convergence easy with diffuse functions? >Regards >Mr.Shabbir >shabbir::nenu.edu.cn> > > >