 ## Firefly and PC GAMESS-related discussion club Learn how to ask questions correctly

Re: Atomic Basis Set

Andrei V Scherbinin
andrei.scherb@gmail.com

Hi,

By default, input contraction coefficients refer to non-normalized primitive Gaussian functions.
Before they are used in calculations, Gaussian primitives are normalized.
As a result, there are two sets of contraction coefficients in the output.
The first one refers to Gaussian primitive before normalization
(i.e, to non-normalized functions, (0.700713) in your example).
This set of coefficients is given in parentheses.
The second one refers to Gaussian functions normalized to unity
(1.801737 in your example, i.e. the number given without parentheses):

> 1 S 3 5.533350 1.801737 ( 0.700713)

A simple "rule of thumb" (just a reminder) is to look at any non-contracted shell, e.g.

5 D 17 0.450000 0.406941 ( 1.000000)

Clearly, ( 1.000000) is the coefficient at the non-normalized primitive Gaussian and is exactly the same
as you specified it in the \$data group, external basis file, etc..., while 0.406941 is the coefficient at
the normalized primitive Gaussian of the normalized shell.

On Fri Aug 12 '11 7:59am, Mikhail Altaisky wrote
------------------------------------------------
>>Can anybody tell me what is written in the ATOMIC BASIS SET section of the PC GAMESS output file between the exponent and the contraction
>coefficient The latter is in ( ), but what number stands before it
>(The output is from 3-21G basis)
> SHELL TYPE PRIM EXPONENT CONTRACTION COEFFICIENTS
>
>
>
> C
>
>
>
> 1 S 1 172.256000 2.093132 ( 0.061767)

> 1 S 2 25.910900 2.936751 ( 0.358794)

> 1 S 3 5.533350 1.801737 ( 0.700713)

> exponent (Contr Coeff)

>Thanks,
>Mikhail Altaisky

[ This message was edited on Sat Aug 13 '11 at 0:06am by the author ]   Sat Aug 13 '11 0:06am   This message read 1310 times