Hi all,
Using VMD I filled between two graphene sheets with a water box, but VMD does not have NH4+ and OH- ions to ionize my water box. I want to use the topo tools plugin of vmd to produce a LAMMPS data file for this system.
I think we can include Param and Top files for NH4+ to the charmm toppar but it is not a straightforward task. I used OpenBabel to generate the PDB file of the desired ions and then used packmol to make the water box with the ion inside that. I can open that pdb file in vmd and everything looks fine but the pdb file format doesn’t look fine. Part of the pdb which is the end of H2O atoms and the beginning of OH is shown below.
ATOM 53994 O HOH B4999 2.995 23.380 -17.954 0.00 0.00
ATOM 53995 H HOH B5000 12.807 -23.484 64.827 0.00 0.00
ATOM 53996 H HOH B5000 11.194 -23.428 64.585 0.00 0.00
ATOM 53997 O HOH B5000 11.982 -22.932 64.948 0.00 0.00
ATOM 53998 H HOH B5001 -25.043 24.943 55.807 0.00 0.00
ATOM 53999 H HOH B5001 -25.452 26.018 56.966 0.00 0.00
ATOM 54000 O HOH B5001 -25.790 25.485 56.192 0.00 0.00
ATOM 54001 O HOH C 1 16.958 12.226 47.560 1.00 0.00 O
ATOM 54002 H HOH C9999 16.028 12.102 47.329 1.00 0.00 H
ATOM 54003 O HOH C 1 -23.213 -1.937 48.734 1.00 0.00 O
ATOM 54004 H HOH C9999 -22.898 -2.053 47.828 1.00 0.00 H
ATOM 54005 O HOH C 1 7.618 -18.981 -36.418 1.00 0.00 O
ATOM 54006 H HOH C9999 7.110 -18.458 -35.783 1.00 0.00 H
As it is shown the residue type for both is similar, HOH, and the residue sequence number for OH- are either 1 or 9999. My question is that is there any way to fix this problem like manually changing the residue type and sequence in pdb or the LAMMPS data file? Or no I should include the topology of the NH4+ and OH- negative to the charmm rtf file and regenerate the psf, and pdb file using that? I will really appreciate it if someone can help me with this.
I used Topo Tools to produce the LAMMPS data file but because my pdb has these issues it also has a similar problem like my pdb
Thank you
Sadra