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
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
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