# Is 'gamma' reserved internal variable?

Jacek Klos jakl at tiger.chem.uw.edu.pl
Tue Jul 1 10:49:00 BST 2003

Dear Molpro users,

I hit the following problem, which I would consider rather
as a bug. I prepared my input wich involved some loop over distances
and used variable gamma to asign result of some calculations. Then
I needed another variable wich was equal to 2*gamma. The result from
Molpro 2000.1 surprisingly to me was different then my check calculations
in Matlab, so after some investigation I concluded, that the problem is
with variable called 'gamma'. Here is simple input, which shows the
problem:

***, bug gamma test
gthresh,energy=1.d-10;
distances=[1.4,1.6,1.8,2.0,2.2,2.4]
geometry={noorient;
H1;
H2,H1,r;
}
basis
sp,h,avdz;c;
end
do i=1,#distances
r=distances(i)
rhf;wf,2,1,0;maxit,90;
gamma(i)=2*i;
gamm(i)=2*i;
gammat(i)=gamma(i);
gammatok(i)=gamm(i);
table,gamma,gammat,gammatok
sort,1
enddo
---

The table output from this input is :

GAMMA     GAMMAT    GAMMATOK
2.0   0.00000000       2.0
4.0   0.00000000       4.0
6.0   0.69314718       6.0
8.0   1.79175947       8.0
10.0   3.17805383      10.0
12.0   4.78749174      12.0

As you see, variable 'gamma' is not reproduced in variable 'gammat'.
When I changed name 'gamma' to 'gamm' for example, everything was ok in
variable 'gammatok'.

I couldn't find description in the Molpro  manual that 'gamma' is
internal variable and cannot be used in the molpro input. Apparently the
parser has problem with it and assigns some value to 'gammat' variable,
but I have no clue what is that number. In my input for my work, the
results were printed and looked reasonably, so if someone would use that
variable would get wrong results and could not notice that. I wanted
to check my results and that's why I found this problem.

Dis someone already discover this or does know explanation

Is there a patch for it, maybe?

Best regards

--
Jacek A. Klos
---------------------------------
Quantum Chemistry Laboratory     |
Department of Chemistry          |
University of Warsaw             |
Pasteura 1 Street                |
02-093 Warsaw                    |
Poland                           |
(+4822)8220211 ext. 213          |
e-mail: jakl at tiger.chem.uw.edu.pl|
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