Dear LAMMPS community,

I’m currently using the 29Sept2021 version of LAMMPS to model wetting of different substrates with water at the tip4p/ice level. For the substrates I’m using harmonic potentials for bonds and angles while the non bonded parameters are described using a lj/long/coul/long pair style. Water molecules are described via the TIP4P model with pppm/tip4p for the long-range coulombic forces. Unfortunately I’m getting Illegal pair_style command as error message. I am now wondering if the 2 pair style are compatible with each other, I’m aware that coupling anything with TIP4P is not trivial due to the presence of the charge on the dummy atom and the long range solver but this set up does not seem to be too much complicated. Does anybody have an advice on that? I’m posting below the relevant part of the input:

units real

atom_style full

boundary p p p

read_data S+w_02

#------Define the interaction Parameters--------#

bond_style harmonic

angle_style harmonic

dihedral_style harmonic

improper_style harmonic

#------Groups------------------------------#

group oxsi type 1

group si type 2

group bulk type 1 2

group oxh type 3

group h type 4

group silanol type 3 4

group slab type 1 2 3 4

group hy type 5

group ox type 6

group water type 5 6

#-----------Define charges-----------------#

set type 1 charge -0.55

set type 2 charge 1.1

set type 3 charge -0.675

set type 4 charge 0.4

set type 5 charge 0.5897

set type 6 charge -1.1794

neighbor 2.0 bin

neigh_modify every 10

timestep 1

variable T equal 100

#########################################################

## FF SETTINGS

#########################################################

pair_style hybrid lj/long/coul/long 8.5 lj/long/tip4p/long 6 5 4 6 0.1577 8.5

pair_modify tail yes

kspace_style pppm/tip4p 1.0e-4

#################SLAB##################

pair_coeff 1 1 lj/long/coul/long 0.04 3.6 #O(si)-O(si)

pair_coeff 1 2 lj/long/coul/long 0.06 3.888

pair_coeff 1 3 lj/long/coul/long 0.08 3.6

pair_coeff 1 4 lj/long/coul/long 0.0265 1.988

pair_coeff 2 2 lj/long/coul/long 0.08 4.2

pair_coeff 2 3 lj/long/coul/long 0.1 3.888

pair_coeff 2 4 lj/long/coul/long 0.0465 2.147

pair_coeff 3 3 lj/long/coul/long 0.12 3.6

pair_coeff 3 4 lj/long/coul/long 0.0665 1.988

pair_coeff 4 4 lj/long/coul/long 0.013 1.098

################WATER#############

############hydrogen_water########

pair_coeff 5 5 lj/cut/tip4p/cut 0.0 0.0

pair_coeff 5 1 lj/long/coul/long 0.0 0.0

pair_coeff 5 2 lj/long/coul/long 0.0 0.0

pair_coeff 5 3 lj/long/coul/long 0.0 0.0

pair_coeff 5 4 lj/long/coul/long 0.0 0.0

pair_coeff 5 6 lj/cut/tip4p/long 0.0 0.0

#############oxygen_water########

pair_coeff 6 6 lj/cut/tip4p/cut 0.21084 3.1668

pair_coeff 6 4 lj/long/coul/long 0.11192 1.8647

pair_coeff 6 3 lj/long/coul/long 0.16542 3.3764

pair_coeff 6 2 lj/long/coul/long 0.14542 3.6469

pair_coeff 6 1 lj/long/coul/long 0.12542 3.3764

bond_coeff 1 285.0 1.68 #Si-O

bond_coeff 2 285.0 1.68 #Si-O(silanol)

bond_coeff 3 495.0 0.945 #O-H

bond_coeff 4 450 0.9572 #H20

angle_coeff 1 100.0 149.0 #Si-O-Si

angle_coeff 2 100.0 109.5 #O-Si-O

angle_coeff 3 100.0 109.5

angle_coeff 4 100.0 109.5

angle_coeff 5 50.0 115.0

angle_coeff 6 55 104.52 #H20

dihedral_coeff * 0.0 1 0

improper_coeff * 0.0 0

#############################################################

# settings

#############################################################

velocity all create $T 12345 rot yes mom yes dist gaussian

velocity si set 0.0 0.0 0.0

fix freeze si setforce 0.0 0.0 0.0

fix fixtip4p water shake 1e-6 200 0 b 4 a 6