Hello,
I use the Lammps Code (Version 2014) to simulate the bombardment of an amoprhous target using a single projectile initialized on top of the surface of my target. In the past the projectile and the target atoms were of the same element, which made it easy to perform the calculations, since I only needed one class of particles and one interaction potential.
In future simulations I want the projectile to be of a different element, which makes thing rather complicate. Now I have to deal with two kinds of interaction events. On the one hand, two particles of the same element may interact with each other, and on the other hand two particles of different elements can interact.
This means I have to change my code to include two types of elements and (at least) two interaction potentials.
I tried to do this with the following approach:
1. Introducing a second mass
mass 1 107.87 (thats the old Ag-mass)
mass 2 39.35 (Ar-mass, thats new)
2. Introducing a second potential
pair_style eam (this potential should simulate the Ag-Ag-Interaction)
pair_coeff 1 1 Ag_u3.eam
pair_style lj/cut 2.0 (this potential should simulate the Ar-Ag-Interaction)
pair_coeff 1 2 1.0 3.65
Bit this doesn’t seems to work. In the log.lammps file the last line says: "Numeric Index out of bounds" after reading
the second mass line. Do you know, how to solve this problem?
Sincerely,
Pawel
Hello,
I use the Lammps Code (Version 2014) to simulate the bombardment of an
amoprhous target using a single projectile initialized on top of the
surface of my target. In the past the projectile and the target atoms
were of the same element, which made it easy to perform the
calculations, since I only needed one class of particles and one
interaction potential.
In future simulations I want the projectile to be of a different
element, which makes thing rather complicate. Now I have to deal with
two kinds of interaction events. On the one hand, two particles of the
same element may interact with each other, and on the other hand two
particles of different elements can interact.
This means I have to change my code to include two types of elements and
(at least) two interaction potentials.
I tried to do this with the following approach:
-
Introducing a second mass
mass 1 107.87 (thats the old Ag-mass)
mass 2 39.35 (Ar-mass, thats new)
-
Introducing a second potential
pair_style eam (this potential should simulate the
Ag-Ag-Interaction)
pair_coeff 1 1 Ag_u3.eam
pair_style lj/cut 2.0 (this potential should simulate the
Ar-Ag-Interaction)
pair_coeff 1 2 1.0 3.65
Bit this doesn’t seems to work. In the log.lammps file the last line
says: “Numeric Index out of bounds” after reading
the second mass line. Do you know, how to solve this problem?
Please review carefully the documentation for create_box and then for pair_style hybrid. The first should solve your immediate problem (with the mass command) and the second how to combine two different potential types. In your input fragment, you replace eam with lj/cut. Only the most recent pair style command is active…
HTH,
Axel
Oh, and you need to look up proper lj parameters and convert them to metal units.