From: |
grzesb (- at -) asp.biogeo.uw.edu.pl (Grzegorz Bakalarski) |
Date: |
Mon, 21 Nov 94 15:41:23 +0100 |
Subject: |
Mulliken charges and basis sets |
Dear Netters,
Maybe this is a very naive question, but ....
I'd like to ask you Dear Quantum Chemists, how much charges from
Mulliken population analysis can depend upon basis set ?
Particular problem is that I and co-workes have calculated Mulliken
charges using different programs using different basis sets eg.
gaussian 6-31G** basis set ( in GAUSSIAN) and double numerical
with polarization basis set (DNP in DMol). And of course we've got
different Mulliken charges. (As we've expected and as it is well
know that Mulliken charges depend on basis sets). But we've noticed
that for some atoms differences are quite large. For example when
a methyl group is bound to nitrogen atom changes are about 0.7-0.8 e
(6-31G** : -0.188 [MP2] ;-0.193 [B3-LYP] and DNP: -0.962 [LDF]; -0.786 [NLDF]).
more negative for numerical basis set.
I'd like to ask especially about comparison between DNP and gaussian+diffusive
basis sets, because as I know numerical basises are "more diffusive" than
gaussian ones.
(they have "good tails".)
I'd like to add that we've also calculated ESP charges and they are O.K.
(diferences
less than 0.1 e), that means that electron density is calculated correctly.
Any comments, references and hints would be nice. Thanks in advance for
anyone who replies. If I get any useful information I'll summarize to the NET.
Best wishes and have a nice week.
Grzegorz Bakalarski
Dept. of Biophys. UW
& Interdisciplinary Centre
for Modelling (ICM)
Warsaw University
Poland
e-mail: grzesb;at;asp.biogeo.uw.edu.pl
P.S. I would NOT like to start next World Chemistry War on which charges are the
best.
Just simple comparison.
bye
Similar Messages
11/25/1994: SUMMARY: Mulliken Population Analysis and Basis Sets
11/26/1995: Combinning Different Basis Sets.
06/30/1994: CCL:SUMMARY:elec.pot.:basisset depend.
02/04/1997: Mulliken Populations Summary
07/07/1995: Summary: Opinions on the quantum charges
07/13/1998: Summary : Mixing basis sets.
11/28/1995: basis set mixing
10/02/1996: SUMARY:PD atomic charges
07/05/1994: Re: CCL:Semi-empirical S-charges II
02/21/1995: charges again
Raw Message Text
|