Subject: Re: CCL:Hyperchem/MNDO

From: [email-masked] (Joel Polowin)
Date: Wed, 15 May 96 09:44:04 -0400

> From: [email-masked] (orcaro)
> Date: Wed, 15 May 1996 12:35:41 +0930 (GMT+0930)
> 
> I'm trying to do single point calculations on H2SO (Hopfinger
> & Pearlstein, J. Comp. Chem., v5, 486-499 (1984)) using the MNDO
> semi-empirical method on Hyperchem. However, I get an error
> message stating that the Slater exponent of the s orbital is less
> than or equal to zero and to check the parameter file mndo_1.abp.
> In the parameter file, the value 1.331967 (clearly not less or
> equal to zero :-) appears. Does anyone know what is going on?

The problem is probably because you have selected only part of the system
for the calculation, and the capping atom which lies along the classical-
quantum boundary is not parameterized.  For example, if I select only
the O atom in H2SO and start an MNDO single-point calculation, I get an
error message: "Capping atom 1 with atomic number 16: the Slater exponent
of s orbital is less then or equal to zero..."  The trivial solution is
to select all of the atoms, or to select none of them so that the entire
system is used.  If you really do want to calculate only part of the
system, you will probably need either to add parameters for the capping
atom(s), or remove the bonds from the system so that none of the atoms
are capping-type.

Joel

------------
Joel Polowin, Ph.D.   Manager, Scientific Support
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