[lammps-users] Creating Stillinger-Weber potential file for Si/Ge

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1

Hi everyone,

I want to create a Stillinger-Weber potential file ‘SiGe.sw’ for Si/Ge interaction.

I tried to read the LAMMPS manual and some example potential files for instruction. The only two examples I can find that deal with interaction of different types of atoms of SW potential are ‘CdTe.sw’ and ‘GaN.sw’, which locate in the ‘potential’ folder of the LAMMPS package.

I have several questions about the two examples:

  1. In the ‘CdTe.sw’, why the 3-body parameters, like Epsilon, are zero in the line of ‘Cd Cd Te’?

  2. In the ‘GaN.sw’, the 3-body parameter ‘Sigma’ in ‘N Ga N’ line and ‘N N Ga’ line are not same. However, in the “pair_style sw command” section of the LAMMPS manual, there is a sentence “Since the order of the two neighbors is arbitrary, the threebody parameters for entries CSiC and CCSi should be the same.” Based on this sentence, the ‘Sigma’ in ‘N Ga N’ line and ‘N N Ga’ line should be the same.

Thanks for your time.

-Zhi

2

Aidan - do you want to respond to these Q?

Steve

3

CdTe.sw was updated on 2009-12-15 to accomodate a change in the SW mixing
rules. Try examining the latest version of LAMMPS.

From: Steve Plimpton <[email protected]>
Date: Fri, 2 Apr 2010 09:18:30 -0600
To: Zhi Li <[email protected]...>, Aidan Thompson <[email protected]>
Cc: "[email protected]" <[email protected]>
Subject: Re: [lammps-users] Creating Stillinger-Weber potential file for Si/Ge

Aidan - do you want to respond to these Q?

Steve

Hi everyone,

I want to create a Stillinger-Weber potential file 'SiGe.sw' for Si/Ge
interaction.

I tried to read the LAMMPS manual and some example potential files for
instruction. The only two examples I can find that deal with interaction of
different types of atoms of SW potential are 'CdTe.sw' and 'GaN.sw', which
locate in the 'potential' folder of the LAMMPS package.

I have several questions about the two examples:

1. In the 'CdTe.sw', why the 3-body parameters, like Epsilon, are zero in
the line of 'Cd Cd Te'?

2. In the 'GaN.sw', the 3-body parameter 'Sigma' in 'N Ga N' line and 'N N
Ga' line are not same. However, in the "pair_style sw command" section of
the LAMMPS manual, there is a sentence "Since the order of the two neighbors
is arbitrary, the threebody parameters for entries CSiC and CCSi should be
the same." Based on this sentence, the 'Sigma' in 'N Ga N' line and 'N N Ga'
line should be the same.

Thanks for your time.

-Zhi

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