Dear all,

Below I have explained the problem I have.

I am using hybrid/overlay pair_style to combine two pair_styles: tersoff and lj/cut/coul/cut.

My input file reads:

pair_style hybrid/overlay tersoff lj/cut/coul/cut 10.0

read_data datafile

pair_coeff * * tersoff BN.tersoff B N

I have defined pair_coeffs of lj/cut/coul/cut for atom type “i” in the datafile as:

Pair Coeffs

1 lj/cut/coul/cut .345345 4.43534

2 lj/cut/coul/cut .145345 1.43534

.

.

Everything works until I try to explicitly define the pair_coeffs of lj/cut/coul/cut for itype!=jtype in the input file.

As Dr. Kohlmeyer has explained in this post http://lammps.sandia.gov/threads/msg24982.html, mixing of pair_coeffs for itype!=jtype would not work with hybrid/overlay if there are more than one interaction per pair of atom types, therefore, must be explicitly defined. When I add the following line to the input file, I get the “Lost atoms” error (“Lost atoms: original 200 current 49”).

Pair_coeff 1 2 lj/cut/coul/cut .23442 .235425

I am wondering if somebody has any idea what is happening.

Thank you,

Navid

Navid Sakhavand

Graduate Research Assistant

Department of Civil and Environmental Engineering

Rice University, Houston, TX 77005

navids@…623…

Dear all,

Below I have explained the problem I have.

I am using hybrid/overlay pair_style to combine two pair_styles: tersoff and

lj/cut/coul/cut.

My input file reads:

pair_style hybrid/overlay tersoff lj/cut/coul/cut 10.0

read_data datafile

pair_coeff * * tersoff BN.tersoff B N

I have defined pair_coeffs of lj/cut/coul/cut for atom type “i” in the

datafile as:

Pair Coeffs

1 lj/cut/coul/cut .345345 4.43534

2 lj/cut/coul/cut .145345 1.43534

.

.

Everything works until I try to explicitly define the pair_coeffs of

lj/cut/coul/cut for itype!=jtype in the input file.

As Dr. Kohlmeyer has explained in this post

LAMMPS Molecular Dynamics Simulator, mixing of pair_coeffs for

itype!=jtype would not work with hybrid/overlay if there are more than one

interaction per pair of atom types, therefore, must be explicitly defined.

When I add the following line to the input file, I get the “Lost atoms”

error (“Lost atoms: original 200 current 49”).

Pair_coeff 1 2 lj/cut/coul/cut .23442

.235425

because you are providing bad potential parameters.

your sigma is very obviously not the sigma resulting from mixing.

axel.

Dr. Kohlmeyer,

Thank you for your quick response. In fact, the numbers I mentioned in the

previous email were simply an example. I have used the geometric mean method

for epsilon and the arithmetic mean method for mixing sigma. The true values

I have used are as follows:

1 1 0.0949091 3.453

2 2 0.144837 3.365

1 2 0.117245 3.409

Sorry for the confusion.

Navid

Dr. Kohlmeyer,

Thank you for your quick response. In fact, the numbers I mentioned in the

previous email were simply an example. I have used the geometric mean method

for epsilon and the arithmetic mean method for mixing sigma. The true values

I have used are as follows:

1 1 0.0949091 3.453

2 2 0.144837 3.365

1 2 0.117245 3.409

Sorry for the confusion.

any advice can only be as good as the description of the problem.

the next question is: are you sure that what you are simulating

is is actually a meaningful model? it looks like you are trying to

use two sets of potentials for the same set of atoms.

thus you'll first have to prove that the model that you

are trying to simulate is meaningful and that lammps

is a error producing high potential energy.

axel.

Well, I am simultaneously using the two set of potentials according to what

I have found in the literature. I will check that with the author.

Thank you for your help.

Navid