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Re: [lammps-users] some questions about "pair style gay-berne"
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Re: [lammps-users] some questions about "pair style gay-berne"


From: Axel Kohlmeyer <akohlmey@...24...>
Date: Mon, 7 May 2018 10:26:37 -0400

On Mon, May 7, 2018 at 9:28 AM, htc <619771202@...1204...> wrote:
>  i read it for many times and i know that the default rule is geometric.

it is not the quantity of reading that matters, but the quality. don't
expect that the manual has the direct answer to your question right
where you look for it and exactly how you would want it to be
formulated. you have to "read around it" to understand the general
principles (e.g. read the pair_coeff, pair_modify, and pair_style
pages very carefully as well).

> Actually ,i am confuse about this : for type i j  and   i!=j    the
> pair_coeff sigma—if i specify its value like D. Do lammps use the value D
> or use the value which caculated by mixing rule(if the two values are
> different)? It says default rule is geometric.Does it means whatever the
> "pair_coeff sigma" is you specify for type i!=j,the lammps will caculate it
> again by "geometric" and use it even though you do not use pair_modify?

again, this is all answered in the manual. please try again in the way
as suggested above.

you can easily verify what explicit settings LAMMPS is using through
writing out the entire force field parameters using the "write_coeff"
command.

axel.


>
>  thanks!
>
>
> The mixing rule for Gay-Berne is explained here:
> http://lammps.sandia.gov/doc/pair_gayberne.html
> and in the papers cited therein.
>
> Giacomo
>
> On Mon, May 7, 2018 at 1:47 AM, htc <619771202@...1204...> wrote:
>>
>> for this command ,i just have to set "epsilon i_a,b,c" for each type  and
>> can set them to zero when i!=j .But for "epsilon " and "sigma" , i still
>> have to assign their value for each pair of atom style right?
>> For i=j , i specify "epsilon" and "sigma"value . Should i do the same
>> thing when i!=j?
>> If i use the command "pair modify mix airthemic", what will happen for
>> type i!=j about the value "epsilon" and "sigma" i just set?
>> Which one have the top priority?
>>
>>
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>
>
>
> --
> Giacomo Fiorin
> Associate Professor of Research, Temple University, Philadelphia, PA
> Contractor, National Institutes of Health, Bethesda, MD
>
>
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>



-- 
Dr. Axel Kohlmeyer  akohlmey@...24...  http://goo.gl/1wk0
College of Science & Technology, Temple University, Philadelphia PA, USA
International Centre for Theoretical Physics, Trieste. Italy.