# [molpro-user] Using numerical grid and weights in an external program

Jayashree yfpjaya at gmail.com
Tue Jun 17 14:35:22 BST 2014

```Indeed, I think I have an issue with the factors. I have been using the
EMSL basis library, which has different exponents from those in the MOLPRO
basis library. Thanks for pointing this out! If I understand correctly, the
library has the following columns for a given basis set:

Basis H s 631G
<http://www.molpro.net/info/basis.php?version=current&describe=1&element=H&basis=631G>
PrimitivesContractions... 13.0077300.0334950.000000 1.9620790.2347270.000000
0.4445290.8137510.000000 0.1219490.0000001.000000
Is the 1st column exponent, 2nd the coefficient? What is the third column
for?

>From your mail, I gather that MOLPRO library basis functions are NOT
normalised-- is this correct? I believe the analogous ones in EMSL are. For
example the same basis above in EMSL is

BASIS "ao basis" PRINT
#BASIS SET: (4s) -> [2s]
H    S
18.7311370              0.03349460
2.8253937              0.23472695
0.6401217              0.81375733
H    S
0.1612778              1.0000000
END

Jayashree

On 16 June 2014 02:00, Gerald Knizia <knizia at theochem.uni-stuttgart.de>
wrote:

> On Wed, 2014-06-11 at 07:17 -0400, Jayashree wrote:
>
> > I generated and saved a 3D grid in a molpro output file. The x,y,z
> > coordinates and weights (w_k) are printed for each atom. [...]
> > If I then sum the atomic contributions, I should get the total number
> > of electrons. My question is:
> > Is there a missing factor involved in this formula?
> > I tried a simple test of evaluating the atomic contribution to the
> > electron ground state density where F stands for
> > F(x,y,z) = sum(AO1,AO2) AO1(x,y,z)* AO2(x,y,z) Denmat(AO1,AO2)
> > , and did not obtain the correct number of electrons.
>
>
> I think this should work. The weights themselves represent the volume of
> their respective integration points, and if you use them to sum the
> number of electrons like this, you should get the total number of
> electrons.
>
> Are you sure that you have all normalization factors correctly applied
> in the AOs themselves? A common problem when evaluating basis functions
> is missing the factors between raw primitive Gaussians and normalized
> primitive Gaussians (i.e., the factor converting between "library
> format" of the contraction coefficients (which refer to primitive
> functions normalized such that Int[r in R^3] mu^2(r) d^3r = 1) to what
> you actually use in the code).
>
> Beware also of the order of basis functions. Molpro's order of solid
> harmonic functions is particularly creative.
> --
> Gerald Knizia
>
>
>
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