Hello,
The following is my input file for using the Soft Potential:
units real
boundary p p p
newton on
atom_style full
pair_style soft 14.0
bond_style harmonic
angle_style harmonic
dihedral_style multi/harmonic
improper_style cvff
read_data 20per8000tol.dat
neighbor 2.0 bin
neigh_modify delay 5
fix fixv all rigid/nvt molecule temp 0.1 0.1 100.0
dump atomdump all custom 10000 20per8000tolsoft.lammpstrj id type mol x y z ix iy iz
restart 1000000 20per8000tolsoft.restart
timestep 0.05
velocity all create 295.0 807006 dist gaussian mom yes rot yes
run 1000000
I have read in the manual that the values for “A” and “cutoff” must be defined for each pair of atoms by the pair_coeff command. I have 9 atom types and so the values for these atoms are located in my data file and look like:
Pair Coeffs
1 0.07 3.55
2 0.07 3.55
3 0.07 3.55
4 0.03 2.42
5 0.07 3.55
6 0.07 3.55
7 0.066 3.50
8 0.03 2.42
9 0.03 2.50
So these are the A and r_{c} values for pairs of identical atoms, but I haven’t defined values for pairs of different atoms (eg. 1 with 2).
Even though the value of A and the cutoff are not defined for all atom pairs - the simulation still works fine. I haven’t included any mixing of the coefficients in my scripts so I’m really not sure what values the pairs of heteronuclear atoms are taking?
Thanks, Simon