[Users-list] Trying to understand electronic term...

[Joseph M Leonard]

Folks, I have been reading the GRID literature base, and the referenced
CHARMM paper, trying to determine the value of the constant, K, mentioned in
the equation for the electronic energy.  The GRID manual states:
--
The electrostatic interaction is:

EQ = p * q * K * [ (1/d) + (M-W)/[ (M+W)*(SQRT(d*d+4*P*Q)) ] ] / M
where p and q are the electrostatic charges on the Probe group and the
pairwise Target atom, and K is a combination of geometrical factors and
natural constants.
--

This is similar to Eq. 3 in J Med Chem 28, 849(1985).  Checking the CHARMM
paper (J Comp Chem 4, 187(1983)) on P. 191, the constant dielectric form of
the electronic energy (Eq. 14) suggests that K = 4pi.

Is this the proper value of K, or is there also a conversion factor to
generate energies in the proper units (such as 332 for kCal/mol)?  If I've
missed a paper providing the proper value, I'd really appreciate the
citation!

Thanks in advance!

Joe Leonard
jleonard42 at gmail.com
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://www.moldiscovery.com/pipermail/users-list/attachments/20070928/a2bf2998/attachment.html