From CUNDARIT@MEMSTVX1.bitnet  Thu Mar  4 01:56:00 1993
Message-Id: <199303041256.AA07805@oscsunb.ccl.net>
Date: Thu, 4 Mar 93 06:56 CDT
From: CUNDARIT%MEMSTVX1.BITNET@OHSTVMA.ACS.OHIO-STATE.EDU
Subject: density functional question
To: chemistry@ccl.net


Hi,

        Our group has just started experimenting with LDF in a small way
for transition metal calcs.  We are trying to calculate the binding energy
of H2 to Cr(CO)5, in conjunction with some work by Ted Burkey in our Dept.
who has made the first exptl. determination of this quantity.  Given our
lack of experience with LDF we want to be sure we are not making any
serious mistakes. We are using DMol at the San Diego Supercomputer Center.
        First question: Are LDF methods size-consistent?
        Second question: Does anybody have any feeling for the effect of
freezing the core density in such calcs. on properties such as energetics
and geometry?
        Third question: I have just calcd. a binding energy of -30 kcal/mol
from E(Cr(CO)5(H2)) - E(Cr(CO)5) -E(H2) using the equivalent of a double-zeta-
valence-plus-polarization basis set, and a FINE mesh size.  Should I believe
this or is it worth the expense to go to a larger basis set, finer mesh,
unfrozen core?
        All suggestions are welcome.

                                        Tom Cundari, Asst. Prof.
                                        Dept. of Chemistry
                                        Memphis State University
                                        Memphis, TN 38152
                                        phone:901-678-2629
                                        fax:901-678-3447
                                        e-mail:cundarit@memstvx1.memst.edu