Subject: van der Waals parameters

From: "Tahmid I. Mizan" <[email-masked]>
Date: Wed, 8 Dec 93 19:45:59 GMT

Hi,

I address my question (probably a trivial question) to any obliging 
molecular dynamics guru:

Weiner, et al. (J. Comp. Chem. 7,230-252,1986) report non-bonded 
parameters for an aliphatic all atom carbon (sp3) as R* = 1.80 
angstrom and epsilon = 0.06 kcal/mol.

I assume this corresponds to a sigma,
       
     sigma = R*/2^(1/6) 

so that for the carbon sigma = 1.604 angstrom

but most other sources give much larger values 
of sigma,

       sigma = 3.35 angstrom  (Allen & Tildesley, p.21)

What am I missing here ? Obviously one value is about double
the other, why ?

Thanks in anticipation.

Tahmid Mizan

[email-masked]
)
What am I missing here ? Obviously one value is about double
the other, why ?

Thanks in anticipation.

Tahmid Mizan

[email-masked]