[lammps-users] about hybrid style

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1

Dear support I have a question about hybrid style:
I try to simulate a gold cluster over a sheet of graphene, the interactiona are described as follow:
gold-gold by eam/opt potentials
graphene-graphene via tersoff potentials
gold-graphene via lj/cut/opt potential

pair_style hybrid eam/opt tersoff lj/cut/opt 8.768
pair_coeff 1 1 eam/opt Au_u3.eam
pair_coeff 2 2 tersoff SiC.tersoff C
pair_coeff 1 2 lj/cut/opt 0.022 2.74 8.768

Howere in the file pair_tersoff.cpp there is some lines the sound strange for me

// insure I,J args are * *

if (strcmp(arg[0],"") != 0 || strcmp(arg[1],"") != 0)
error->all(“Incorrect args for pair coefficients”);

this mean that
pair_coeff 2 2 tersoff SiC.tersoff C

is not valid and must be substituted with
pair_coeff 2 2 tersoff SiC.tersoff C

but I want to describe the tersoff interaction only for atoms of type 2. How can I do this?

Best regard.

Nicola

2

but I want to describe the tersoff interaction only for atoms of type 2. How
can I do this?

pair_coeff * * tersoff SiC.tersoff NULL C

The doc page for Tersoff explains this.

Steve

3

Thanks for the answer, now the pair interaction are set via the commands
pair_style hybrid eam/opt tersoff lj/cut/opt 8.768
pair_coeff 1 1 eam/opt Au_u3.eam
pair_coeff * * tersoff SiC.tersoff NULL C
pair_coeff 1 2 lj/cut/opt 0.022 2.74 8.768

but when lammps start it going in segmentation faut. Why?

N.

2010/4/14 Steve Plimpton <[email protected]>

4

Hi Nicola,

I may be wrong (Steve correct this). But when i use the pair_style hybrid the commands i use are in the following order.

pair_style hybrid tersoff eam/opt lj/cut/opt 8.768
pair_coeff * * tersoff SiC.tersoff NULL C
pair_coeff 1 1 eam/opt Au_u3.eam
pair_coeff 1 2 lj/cut/opt 0.022 2.74 8.768

Best regards,
RD

nicola varini wrote:

5

It seem is order independent, the code produce the following output
LAMMPS (7 Jul 2009)
Reading data file …
orthogonal box = (-88.2 -101.85 -10) to (88.2 101.85 150)
1 by 1 by 1 processor grid
67475 atoms
67475 velocities
Setting up run …
ERROR: 0031-250 task 0: Segmentation fault

N.

2010/4/14 Ram D <rmd.lammps@…36…24…>

6

Posted a patch for this. It was a bug with eam/opt not
doing the right thing in conjunction with pair_style hybrid.

Steve