Error when using the Tip5pwater molecule model

Dear Lammps users/developers,

I’m performing a simulaion on the equilibrium of a cluster which is formed by the condensation of water moleciles (rigid Tip5p) on an acetic acid (nonconstrained) cluster. However, my simulation will go wrong after several steps, although I change of timestep to 0.1 fs.

Following is my “in” file, and the data file is in the attachment.By the way, if I use the spce water model to replace the Tip5p ater model, the simulation is successful.

I cannot find tne reason for this error in the manual. Would you please give me some suggestions?

I would appreciate any help and suggestion.

Thanks so much!

Best regards!

Chao

1. Initialization:

processors 2 2 2

units real

boundary p p p

dimension 3

atom_style full

2. Atom definition:

read_data 120ch3cooh.lammps05

mass 1 12.011 # C (-H)

mass 2 12.011 # C (-C)

mass 3 15.9994 # O (=O)

mass 4 15.9994 # O (-H)

mass 5 1.008 # H (C-H)

mass 6 1.008 # H (O-H)

mass 7 15.999400

mass 8 1.008

mass 9 1.0e-6

group acetic type 1 2 3 4 5 6

group water type 7 8 9

neighbor 2.0 bin

neigh_modify every 1 delay 0 check yes page 300000 one 5000 exclude molecule water

timestep 1

3. Force fields:

pair_style lj/cut/coul/long 14.0

I J eps(kcal/mol) sigma(A)

pair_coeff 1 1 0.066 3.5 #C(CH)

pair_coeff 1 2 0.0832 3.625

pair_coeff 1 3 0.1177 3.23

pair_coeff 1 4 0.1059 3.25

pair_coeff 1 5 0.0445 3.0

pair_coeff 1 6 0 0

pair_coeff 1 7 0.1027 3.31

pair_coeff 1 8 0 0

pair_coeff 1 9 0 0

pair_coeff 2 2 0.105 3.75 #C(C=O)

pair_coeff 2 3 0.1485 3.355

pair_coeff 2 4 0.1336 3.375

pair_coeff 2 5 0.0561 3.125

pair_coeff 2 6 0 0

pair_coeff 2 7 0.1296 3.435

pair_coeff 2 8 0 0

pair_coeff 2 9 0 0

pair_coeff 3 3 0.21 2.96 #O(=O)

pair_coeff 3 4 0.1889 2.98

pair_coeff 3 5 0.0794 2.73

pair_coeff 3 6 0 0

pair_coeff 3 7 0.1832 3.04

pair_coeff 3 8 0 0

pair_coeff 3 9 0 0

pair_coeff 4 4 0.17 3.0 #O(OH)

pair_coeff 4 5 0.0714 2.75

pair_coeff 4 6 0 0

pair_coeff 4 7 0.1649 3.06

pair_coeff 4 8 0 0

pair_coeff 4 9 0 0

pair_coeff 5 5 0.03 2.5 #H(CH)

pair_coeff 5 6 0 0

pair_coeff 5 7 0.0693 2.81

pair_coeff 5 8 0 0

pair_coeff 5 9 0 0

pair_coeff 6 6 0 0 #H(OH)

pair_coeff 6 7 0 0

pair_coeff 6 8 0 0

pair_coeff 6 9 0 0

pair_coeff 7 7 0.1599 3.12 #O-O

pair_coeff 7 8 0 0

pair_coeff 7 9 0 0

pair_coeff 8 8 0 0 #H-H

pair_coeff 8 9 0 0

pair_coeff 9 9 0 0

bond_style harmonic

N k/2(kcal/mol/A^2) r0(A)

bond_coeff 1 340 1.09 #c-h

bond_coeff 2 317 1.522 #c-c

bond_coeff 3 570 1.229 #c=o

bond_coeff 4 450 1.364 #c-o

bond_coeff 5 553 0.945 #o-h

angle_style harmonic

N k/2(kcal/mol/rad^2) theta0(degree) K_UB(en/dis^2) rub(A)

angle_coeff 1 33 107.8 #H-C-H

angle_coeff 2 35 109.5 #H-C-C

angle_coeff 3 80 120.4 #C-C=O

angle_coeff 4 70 108 #C-C-O

angle_coeff 5 80 121 #O=C-O

angle_coeff 6 35 113 #C-O-H

dihedral_style opls

N K1(kcal/mol) K2 K3 K4

dihedral_coeff 1 0 0 0 0 #H-C-C=O

dihedral_coeff 2 0 0 0 0 #H-C-C-O

dihedral_coeff 3 1.5 5.5 0 0 #C-C-O-H

dihedral_coeff 4 0 5.5 0 0 #O=C-O-H

kspace_style pppm 1.0e-4

variable T equal 100

velocity all create 100 87287 loop all dist gaussian

fix a1 acetic nvt temp $T $T 100

fix b1 water rigid/nvt molecule temp $T $T 100

compute t1 acetic temp

compute t2 water temp

thermo_style custom step temp c_t1 c_t2

thermo 500

dump 1 all custom 5000 dump.meltq401 id type x y z mass q

run 1000000

9263609F@...6415....png

120ch3cooh.lammps05 (507 KB)

Dear Lammps users/developers,

I’m performing a simulaion on the equilibrium of a cluster which is formed
by the condensation of water moleciles (rigid Tip5p) on an acetic acid
(nonconstrained) cluster. However, my simulation will go wrong after several
steps, although I change of timestep to 0.1 fs.

on the other hand, using 1fs is *definitely* going to be too large.
rigid body integrators cannot be treated similar to fix shake.

Following is my “in” file, and the data file is in the attachment.By the
way, if I use the spce water model to replace the Tip5p ater model, the
simulation is successful.

I cannot find tne reason for this error in the manual. Would you please
give me some suggestions?

the problem is likely due to bad parameters describing the interaction
between your water and your acetic acid, or between water molecules by
themselves.

i would suggest, you try running pure water first and figure out what
are the settings and parameters that can reproduce published TIP5P
properties correctly.

axel.