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

[Susi Lehtola]

On Tue, 17 Jun 2014 09:35:22 -0400
Jayashree <yfpjaya at gmail.com> wrote:
> 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


What Gerald probably was referring to is that the coefficients you see
are coefficients for the *normalized* primitives. Naturally when you
work this out in a program, you always convert the contraction
coefficients to those of unnormalized primitives, because then you save
on multiplications and don't have to keep track of what coefficient to
apply e.g. in recursion relations (that apply to unnormalized
primitives).

Now, the second thing is that the contractions themselves may be
unnormalized. For instance, I'm ready to put good money that the one in
your example is not normalized. That's because the s primitive with
exponent 0.1612778 should also occur in the contraction, but the EMSL
basis set library often drops the redundant primitives out because they
don't affect the freedom of the basis set: if you have the same
primitive both as a free function and as a part of a contraction, you
can drop the function from the contraction without making any
approximations.
-- 
---------------------------------------------------------------
Mr. Susi Lehtola, PhD             Research Associate
susi.lehtola at alumni.helsinki.fi   Department of Applied Physics
http://www.helsinki.fi/~jzlehtol  Aalto University
                                  Finland
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Susi Lehtola, FT                  Tutkijatohtori
susi.lehtola at alumni.helsinki.fi   Fysiikan laitos
http://www.helsinki.fi/~jzlehtol  Aalto-yliopisto
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