From owner-chemistry@ccl.net Thu Nov 19 11:02:00 2009 From: "John McKelvey jmmckel*o*gmail.com" To: CCL Subject: CCL: Computing volumes in G03 Message-Id: <-40720-091119093201-12603-XFmqvb1kHyxRkJjJwGaucQ() server.ccl.net> X-Original-From: John McKelvey Content-Type: text/plain; charset=ISO-8859-1 Date: Thu, 19 Nov 2009 09:31:45 -0500 MIME-Version: 1.0 Sent to CCL by: John McKelvey [jmmckel]^[gmail.com] Folks, I have been computing volumes using CISD/6-311G* SCF=TIGHT VOLUME=TIGHT for first and second row atoms with charges of +1, 0, and -1 (and of course the appropriate multiplicities.) I find differences between replicate runs to be as large as 20 percent. I know that the answers are supposed to be approximate, but is there any way to tighten this up, perhaps by putting more points "in the box", or any other means? Many thanks! John -- John McKelvey 10819 Middleford Pl Ft Wayne, IN 46818 260-489-2160 jmmckel^_^gmail.com