Subject: Re:G:basis set notation

From: uccatvm <[email-masked]>
Date: Wed, 7 Apr 1999 22:17:21 +0100 (BST)

> In the Szabo I found that 6-31** may be written as (11,4,1;4)/[4,2,1;2]:
> the 6-31** Pople basis set is made from 1 s contracted of 6 gaussians
> for
> the core region for heavy atoms, 2 sp contracted from 3 and 1 gaussians
> for valence and H atoms, plus one set of d polarization functions on
> heavy atoms and 1 set of p functions for hydrogens. Thus, this gives:
> *for the uncontracted part
>         for heavy atoms I counted       6+3+1 s symmetry orbital
>                                         3+1   p symmetry orbitals
>                                         1     d symmetry orbital
>         for the hydrogens I counted     3+1 s symmetry orbitals
>                                         1   p symmetry orbital
> *for the contracted part
>         for heavy atoms I counted       1+1+1 s symetry orbitals
>                                         1+1   p symetry orbitals
>                                         1     d symetry orbital
>         for hydrogens I counted         1+1 s symetry orbitals
>                                         1   p symetry orbital
> so one can write the 6-31** basis set as (10,4,1;4,1)/[3,2,1;2,1]
> and I don't understand the Szabo notation: (11,4,1;4,1)/[4,2,1;2,1].
>
> I wonder what I am doing wrong. If you had any ideas on this matter, I
> would be glad to hear about it.
>

Your calculation looks fine  to me. The 6-31G** basis set consists of 
(4s,1p) contracted to [2s,1p] for H-He, and (10s,4p,1d) contracted to [3s2p1d].

I just looked in my copy of Szabo and Ostlund, and I think they just use
a slightly different notation. The 6-31G** basis set contains a set of d
functions. For 6-31G**, these are Cartesians, i.e, 6 linear combinations
of the usual 5 d functions: 3d(xy), 3d(x2-y2), 3d(yz), 3d(zx), and 
"3d"(x2+y2+z2). The latter one is a function of s-type symmetry, and 
Szabo and Ostlund list this one under the s functions. That's where the 11s
come from.

Hope This Helps,

Tanja
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     Tanja van Mourik                                                
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