CCL: Basis set for B3LYP



"[CCL]"

On 9/14/05, Antonio Hernandez <pescaomayor%a%gmail.com> wrote:
Dear Tsuru:
 
In theory, you can use any contracted or uncontracted Gaussian basis set with B3LYP functional calculations.  Nevertheless, mostly all these basis sets were optimized at the HF level of theory (or HF+correlation level).
 
For consistency, I would prefer to use basis sets optimized at the Density Functional Theory level of theory, as those described by Salahub in:
 
N. Godbout, D. R. Salahub, J. Andzelm and E. Wimmer, Can. J. Chem. 70 (1992)  560.  
   
   You can get these at the website 
    http://www.emsl.pnl.gov/forms/basisform.html
    under DZVP(DFT Orbital) , DZVP2(DFT orbital) and TZVP(DFT Orbital) or DGauss Polarized     DFT Orbitals Basis Sets.
 
I have personally obtained  excellent results with this DFT + Salahub basis sets combination
(see for instance:  Theor. Chem. Acc. 106 (2001) 218).                                
 
Best Whishes: Antonio Hernandez.
 
 
=====================================================
On 9/13/05, CCL <owner-chemistry%a%ccl.net > wrote:

Sent to CCL by: errol lewars [elewars-$-http://trentu.ca/" target="_blank"> trentu.ca]
2005 Sept 14

Hello,

The B3LYP functional is normally used with the 6-31G* basis set or
higher (e.g. 6-31G**, 6-311G*--of course there are other basis sets
besides these Pople sets; the Dunning correlation-consistent sets are
also popular). It is generally thought that the use of a smaller basis
with a correlated method (DFT or correlated ab initio) is pointless, but
I know of no definitive study of this.

A rare case of B3LYP/3-21G is the calc. of IEs of carbenes by
optimization at this level followed by B3LYP/6-31+G* single point
energies: H M Muchall et al., Can J Chem, 1998, 76, 221. The 3-21G basis
was better than the 6-31G* with CASSCF (not a DFT method) in a study of
the Cope rearrangement: D A Hrovat et al., J Am Chem Soc, 1999, 121, 169.

E. Lewars
===



CCL wrote:

>Sent to CCL by: "Telkuni Tsuru" [telkuni : venus.dti.ne.jp]
>Hello, CCLers.
>
>I like to know suitable basis set level for B3LYP on G98W.
>
>For example, MP2 calculation should not be carried out with
>low level basis set(e.g . STO-3G). So I like to know lowest basis
>set for B3LYP. Is "B3LYP/STO-3G" possible ?
>
>  All responses, I will appreciate.
>  I will summarize them and send to CCL.
>
>
>  Thanks in advance
>---------------------------------------------------
>       Telkuni Tsuru     telkuni%a%venus.dti.ne.jp>
>
>
>
>



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