Subject: DFT.comparison

From: [email-masked] (Mori, Seiji)
Date: Sat, 26 Aug 1995 11:33:11 +0900

Mike Frisch wrote:

> >  Seiji Mori wrote:
>>
>> > Utility of DFT is fastly increasing in the application of DFT method .
>> > Now Becke3LYP is known as the best method of DFT, but I think that the
>>
>> Finally I'd like to state that one should always mention what kind of
>> systems he is refering to. It is for example known, that the hybride-
>> methods give excellent results for main-group (mainly C,H,O,N) molecules,
>> but might as well fail for transtion metals.
>>
>
>Certainly one should specify the method, basis set, and types of
>elements/properties considered in making any blanket summary.  There
>is, in fact, a recent study of transition metal structures and
>energies by Rich Martin suggesting that B3LYP with a big basis set is
>pretty good for these systems as well.

 OK. I cannot say and cannot conclude that in all systems B3LYP method is
the best.

 In the Hehre's reference which Dr. Lewars cite, structual parameter of the
hypervalent 
compounds at the  
HF/6-31G* is the better than  one at the SVWN, B3LYP and MP2/6-31G*. 
As I cited to the references in the previous letter, 
 Availability of the B3LYP is likely to expand the system including first
transition metals. 
 For example, 
In M. Holthausen, et al's ref(CPL,1995,240,245), about dissociation
energies for 
MCH2+(M=Sc-Cu), B3LYP rasults are also better 
agreement with the experimental ones than HF ones.  They also were found
that the 
selection of the basis sets are influence to the results. (in this case,
Wachters 
all electron basis sets gave the better results than Dolg or Hay&Wadt ECP.)

 In the Bauschlicher,Jr's ref.(JPC,1994,12899), in the Fe(CO)5+ system, 
B3LYP gave better results than MP2 with the respect to bond length,
harmonic frequencies.
And in my unpublished results, about the harmonic frequencies of MeCu,
B3LYP results are 
better agreement with experimental and CCSD(T) ones, which was reported by
others, than 
MP2 results(Wachters functions and Hay d function for Cu and 6-31G* basis
for other elements 
basis sets are chosen). 
 However still more studies are nessesary, I think. 

 By the way, I 'd like to know Rich Martin's reference.

 Sincerely,
 Seiji Mori
 ============================(^-^)===========================
  Seiji Mori
 Nakamura Lab.
 Department of Chemistry
 The University of Tokyo
 Tel: 03-3812-2111 ext.4647
FAX: 03-5800-6889
 Address: 7-3-1, Hongou, Bunkyo-ku, Tokyo 113, JAPAN
 email: [email-masked]