From owner-chemistry@ccl.net Mon Aug 25 01:00:00 2008
From: "lizhe3[*]mail.ustc.edu.cn lizhe3[*]mail.ustc.edu.cn" <owner-chemistry(_)server.ccl.net>
To: CCL
Subject: CCL:G: How to do Double 3d Shell Calculation
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Date: Sun, 24 Aug 2008 09:33:25 +0800
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Sent to CCL by: "lizhe3-*-mail.ustc.edu.cn" [lizhe3-*-mail.ustc.edu.cn]

Dear All,

I read in literature that the 3d shell of transition metals has a
correlation effect called "3d double shell effect"(eg. K Andersson, BO
Roos. Chem Phys Letters 191:507–514, 1992.and TH Dunning Jr, BH Botch,
JF Harrison. J Chem Phys 72:3419–3420, 1980.). They described the way to
address this problem by adding a second more diffuse d shell to the
electron configuration in CASSCF calculation, eg. the original
configuration of Cu atom is 3d(10)4s(1) can be transformed to
3d(9)3d'(1)4s(1), with 3d' a more diffuse shell. But I do not know how
to do this practically. It seems in the CASSCF method of Gaussian
software I can only include the 3d orbital. Should I also include the 4d
orbital or just use more diffuse basis set? Does anyone know how to add
the 3d' orbital?