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

Sham K shaawm at gmail.com
Wed Jun 18 14:16:54 BST 2014

The difference in exponents between Molpro library and EMSL is surprising.
It is caused by the fact that 6-31G basis specification involves additional
scaling factor for inner and outer valence contractions (the first and
second contractions). This is explained in the "Molecular Electronic
Structure Theory" book by Helgaker.

For Hydrogen the inner valence and outer valence have scaling factors
sqr(1.2) and sqr(1.15). The Molpro library entry does not include this
scaling factor but the program adds it later, whereas EMSL includes it
right away


On Tue, Jun 17, 2014 at 7:05 PM, Jayashree <yfpjaya at gmail.com> wrote:

> 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 1.9620790.234727
> 0.000000 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
> 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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