On Sat, Jan 16, 2021, Loki wrote:
>
>>NonUniversalWarning: Modified off-diagonal LJ parameters detected
>You may ignore this message: it's expected with CHARMM force fields.
>
>Could I please ask why?
There may be two types of questions here:
1. What is a "modified off-diagonal" LJ term?
Generally, force fields assign epsilon and Rmin parameters to atom types.
The LJ parameters for interactions between two different atoms types
are determined by so-called mixing rules. A "modfied" LJ parameter sets
specific epsilon/Rmin parameters for interactions between a pair of
atom types, over-riding the use the the usual mixing rules.
2. Why did the CHARMM developers decide to incorporate these into their FF?
I don't know. You'd have to read the papers that describe the
particular CHARMM FF you are using.
....hope this helps...dac
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Received on Sat Jan 16 2021 - 11:30:02 PST
