From owner-chemistry@ccl.net Sat Apr 25 16:50:01 2009 From: "Huo-Lei Peng horaldraman]_[gmail.com" To: CCL Subject: CCL:G: Questions about SAC-CI calculations. Message-Id: <-39164-090425025429-7423-oZK/3J9WR4n2ph98FALhQQ . server.ccl.net> X-Original-From: "Huo-Lei Peng" Date: Sat, 25 Apr 2009 02:54:25 -0400 Sent to CCL by: "Huo-Lei Peng" [horaldraman : gmail.com] Hi All: Recently, I'v been working on the calculations on a doublet radical, which has 11 carbon, nitrogen or oxygen atoms, using SAC-CI in Gaussian 03. It looks SAC-CI needs a lot of disk space and computer resource. In my case, the computation generated a huge rwf or scr file (up to several hundred GB) and failed finally. Could you give me any suggestion? Here is the input: %nprocshared=4 %mem=16GB %rwf=1.rwf,30gb,2.rwf,30gb,3.rwf,30gb,4.rwf,30gb,5.rwf,30gb,6.rwf,-1 # SAC-CI=(Full, MaxR2Op=1000000, AnionDoublet=(Nstate=3))/6-31G(d) ROH #P GFINPUT IOP(6/7=3) ---------------------------------------------------------------------- BTW, if I use CASSCF to calculate the doublet radical, how to select the active space? Initial open- shell calculation gave me alpha and beta orbitals. So how to select the orbitals in this case. Any suggestions will be highly appreciated Thanks. Huo-Lei Peng Department of Chemistry The Ohio State University 100 W. 18 Avenue Columbus, OH 43210