Subject: Re: CCL:HyperChem formation energy calculation

From: [email-masked] (Joel Polowin)
Date: Tue, 26 Sep 95 15:22:03 -0400

> Date: Tue, 26 Sep 1995 13:47:07 -0400 (EDT)
> From: "Todd J. Raeker" <[email-masked]>
> 
> I am using Hyperchem with pm3 to calculate heats of formation of a few 
> cubane derivatives.  Page 102 of the manual states that the heat of 
> formation is calculated by subtracting atomic heats of formation from the 
> total energies.  I would like to look at these atomic heats of formation 
> that HyperChem is using.  Does anybody know the name of the file or a 
> reference of where I might find these.  I ask because the total energy 
> appears to be O.K. but the reported heat of formation in the log file 
> seems nonsense.  I want to thoroughly check all aspects of this calculation.

The atomic heats of formation for PM3 are the last column of the file 
PM3_1.ABP; the file format is described on page 425 of the Reference manual.
The references for the parameters are: J.J.P. Stewart, _J. Comp. Chem._ *12*,
320 (1991) and J.J.P. Stewart _et al._, QCPE #506.  We have not yet had any
reports of calculation results from HyperChem that differed from the results 
of the same calculation being performed by other standard versions of 
modelling software.

Joel

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