Dear LAMMPS users,
I am making some simulations about some ionic liquids. At first, I make a test.
In the test, I only put one molecular [(EMI+)(FSI-) in a big box. There is no overlaps between the cation and anion. But after a few steps, the positive charged atoms in cation attracts the negative charged atom in anion, and the two attracted atoms are highly overlapped. And the fix nve/limit can not resolve this problem.
I have checked the force field parameters and nothing is wrong. I do not know how to remove this question.
My in.file is below,
units real
boundary p p p
atom_style full #uncharged molecules, with bond, angle, dihedral, improper dihedral
bond_style harmonic
angle_style harmonic
dihedral_style opls
improper_style cvff
pair_style lj/cut/coul/long 12.0
#pair_style soft 2.5
pair_modify mix geometric tail yes
kspace_style pppm 1.0e-4
#read_restart restart.mix.*
read_data data.il
#read_restart restart.mix.*
#fix 1 all shake 0.0001 20 10 b 3
neighbor 2.0 bin
neigh_modify delay 0 every 1 check yes #delay 3
velocity all create 300.0 4567712 rot yes dist gaussian
compute 1 all temp
fix 2 all langevin 300.0 300.0 100.0 48279
fix 3 all nve/limit 0.1
timestep 0.1
dump 1 all custom 20 dump.atom.lammpstrj id q x y z
dump 2 all custom 200000 dump.force.* id mol type element fx fy fz
dump_modify 1 flush yes
dump_modify 2 flush yes
thermo_style custom step c_1 pe etotal vol lx ly lz
thermo 1000
thermo_modify flush yes
restart 100000 restart.mix.*
run 200000
And my force field parameters:
28 atoms
27 bonds
46 angles
47 dihedrals
5 impropers
15 atom types
13 bond types
23 angle types
25 dihedral types
2 improper types
0.000000000 24.000000000 xlo xhi
0.000000000 24.000000000 ylo yhi
0.000000000 24.000000000 zlo zhi
Masses
1 14.00 #N
2 12.00 #CR
3 1.00 #HR
4 12.00 #CW
5 12.00 #Cm
6 1.00 #Hw
7 1.00 #Hm
8 12.00 #Ca
9 1.00 #Ha
10 12.00 #Ct
11 1.00 #Ht
12 32.00 #Sbt
13 16.00 #Obt
14 19.00 #FSI
15 14.00 #Nbt
Pair Coeffs
1 1 0.170 3.25
2 2 0.070 3.55
3 3 0.030 2.42
4 4 0.070 3.55
5 5 0.066 3.50
6 6 0.030 2.42
7 7 0.030 2.50
8 8 0.066 3.50
9 9 0.030 2.50
10 10 0.066 3.50
11 11 0.030 2.50
12 12 0.250 3.55
13 13 0.210 2.96
14 14 0.053 2.95
15 15 0.170 3.25
Bond Coeffs
1 367.00 1.069 # CR-HR
2 367.00 1.068 # CW-H2
3 340.00 1.080 # CA-HA, CM-HM
4 340.00 1.084 # CT-HT
5 477.00 1.315 #CR-NA
6 427.00 1.378 #CW-NA
7 520.00 1.336 #CW-CW
8 337.00 1.476 #NA-CA
9 337.00 1.465 #NA-CM
10 268.00 1.521 # CA-CT
11 374.62979 1.57 #N-S
12 636.64374 1.437 #S-O
13 224.39572 1.575 #F-S
Angle Coeffs
1 33.00 109.80 # HM-CM-HM
2 37.50 109.20 # HM-CM-NA
3 70.00 126.40 # CM-NA-CR
4 70.00 125.60 # CM-NA-CW
5 35.00 125.10 # NA-CR-HR
6 70.00 109.80 # NA-CR-NA
7 70.00 107.90 # CR-NA-CW
8 70.00 107.10 # NA-CW-CW
9 35.00 122.00 # NA-CW-HW
10 35.00 130.90 # HW-CW-CW
11 70.00 125.30 # CW-NA-CA
12 70.00 126.80 # CR-NA-CA
13 37.50 107.50 # NA-CA-HA
14 37.50 111.20 # HA-CA-CT
15 33.00 108.90 # HA-CA-HA
16 37.50 110.70 # CA-CT-HT
17 33.00 107.90 # HT-CT-HT
18 58.35 112.60 # NA-CA-CT
19 115.72084 118.50 #O-S-O
20 94.22471 113.60 #O-S-N
21 80.1328 125.60 #S-N-S
22 107.7195 103.00 #F-S-N
23 128.61852 104.10 #F-S-O
Dihedral Coeffs
1 0.000 0.000 0.000 0.000 # HM-CM-NA-CR
2 0.000 0.000 0.124 0.000 # HM-CM-NA-CW
3 0.000 4.651 0.000 0.000 # CM-NA-CR-HR
4 0.000 4.651 0.000 0.000 # CM-NA-CR-NA
5 0.000 3.000 0.000 0.000 # CM-NA-CW-CW
6 0.000 3.000 0.000 0.000 # CM-NA-CW-HW
7 0.000 4.651 0.000 0.000 # NA-CR-NA-CA
8 0.000 10.750 0.000 0.000 # NA-CW-CW-HW
9 0.000 10.750 0.000 0.000 # NA-CW-CW-NA
10 0.000 4.651 0.000 0.000 # HR-CR-NA-CW
11 0.000 3.000 0.000 0.000 # CR-NA-CW-HW
12 0.000 3.000 0.000 0.000 # CR-NA-CW-CW
13 0.000 4.651 0.000 0.000 # HR-CR-NA-CA
14 0.000 3.000 0.000 0.000 # HW-CW-NA-CA
15 0.000 3.000 0.000 0.000 # CW-CW-NA-CA
16 0.000 0.000 0.000 0.000 # CR-NA-CA-HA
17 0.000 0.000 0.318 0.000 # HA-CA-CT-HT
18 0.000 10.750 0.000 0.000 # HW-CW-CW-HW
19 0.000 4.651 0.000 0.000 # CW-NA-CR-NA
20 0.000 0.000 0.350 0.000 # NA CA CT HT
21 -0.599 -1.750 0.290 0.000 # CW NA CA CT
22 -0.555 0.479 0.200 0.000 # CR NA CA CT
23 -0.755 -2.125 0.400 0.000 #CW NA CA HA
24 0.0000 0.0000 -0.00358 0.0000 # O-S-N-S
25 2.73359 -3.62711 -0.76717 0.0000 # F-S-N-S
Improper Coeffs
1 1.00 -1 2 #x NA xx
2 1.10 -1 2 # x cw xx, x cr xx
Thank you very much in advance.
PingWu.