Subject: CCL:HyperChem

From: "Schriver,M;Chemistry;" <[email-masked]>
Date: Tue, 31 May 1994 18:13:56 +0200 (IST)

Hi,

I've been lurking here recently and was hesitant to post but Rafael
Najmanovich posted a request yesterday that struck home. Last year I
wanted a software package that would 1) give publishable semi-empirical
calculations on small molecules 2) be easy to use and 3) generate
high quality graphics output of molecules and orbitals. After some
looking around I chose HyperChem. I guess the biggest selling point for
me was that AutoDesk was behind it. In all I have now spent $ 2000 [Can]
on the program, up-grades and add-on modules [HyperChem 3 + ChemPlus].

I have to say that it is a very easy program package to use and it provides
excellent graphics output of results. Since I consider myself barely able to
appreciate what eigenvalues and eigenvectors are I took it on faith that the
programmers knew what they were up to. All I wanted from the program were
the energies and compositions of the frontier orbitals of small molecules
and the atomic charges. The only reviews that I have seen have been
fairly superficial [ex. J. Chem. Ed. (1993) A144].

To make a long story short a couple of chemists more familiar with theoret-
ical chemistry that I recently talked to were so negative on the program I am
seriously reconsidering publishing anything I get from the package even if
it confirms my experimental results. They said that the parameterisation
of the package was so poor that the only reliable results would be on the
exact same molecules that HyperChem used to create the parameter files.
Since I am looking at S and P in small hetercycles I was warned very strongly
against using HyperChem in AM1 or PM3 calculations.

They then proceded to tell me that the only reliable results would come 
>from programs that have names that encompass half the alphabet and most
of the alternate characters on the keyboard. Leaving me with the idea 
that these calculations should be left to the professionals. Oh well.

Before I throw away my copy of HyperChem could this list please address
this issue? Where are semi-empirical calculations reliable? Is there a 
difference between AM1 in HyperChem and AM1 in the original manuscripts?
If Rafael gets any personal answers could he please post them here?
			Thanx in advance
							Mel
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+ M.J. Schriver, Assist. Prof.,     + Ph.  (709) 737-8744              +
+ Memorial University of NFLD       + Fax  (709) 737-3702              +
+ St. John's, NFLD, Canada, A1B 3X7 + eml  [email-masked]   +

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From: Rafael N Szeinfeld <[email-masked]>
Date: Tue, 31 May 1994 20:31:56 -0300 (BDT)

He follows the answer not asking for a replay of the answers that I 
received. Hope that they are useful.

			Rafael Najmanovich

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