Re: vdwGeometricSigma for OPLS in NAMD 2.6b1 Release

From: Jim Phillips (jim_at_ks.uiuc.edu)
Date: Mon Aug 22 2005 - 17:40:53 CDT

That is correct. Epsilon always uses the geometric mean. -Jim

On Sat, 13 Aug 2005, Joshua D. Moore wrote:

> Ok, my knowledge of CHARMM is not very good.
>
> The Epsilon,ij is already calculated with the geometric rule. Is this
> correct? So there is no need to add an option for epsilon, correct?
>
> Thanks.
>
> Joshua Moore
>
>
> On Wed, August 10, 2005 7:59 pm, Joshua D. Moore wrote:
>> Hi,
>>
>> I wanted to thank everyone for adding OPLS support in the latest release
>> of NAMD.
>>
>> However, only the geometric combining rule for sigma is added, right?
>> OPLS-AA uses the geometric combining rule for both sigma and epsilon,
>> which I have altered thanks to Ben Roberts in the LJTable.C file. Thanks
>> again Ben! Is it possible to add an option (vdwGeometricEpsilon or
>> similar) for the geometric combining rule for epsilon as well?
>>
>> Furthermore, some may wish to use the Lorentz-Berthelot mixing rules for
>> interactions between unlike atoms in different molecules. These use the
>> arithmetic mean for sigma and the geometric mean for epsilon. Would it be
>> possible to add this? I have not investigated this much, especially with
>> OPLS, but it is just a related thought.
>>
>> Thanks.
>>
>> Joshua Moore
>>
>>
>>
>
>
>

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