error using msi2lmp with the cff91 force field

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1

Hello everyone,

I am trying to form the LAMMPS input file using the tool msi2lmp and the force field cff91. However when executing msi2lmp, I am getting a huge amount of errors/warnings:

" Unable to find endbonddihedral data for 604 610 719 610
Unable to find midbonddihedral data for 604 610 719 610
Unable to find angledihedral data for 604 610 719 610
Unable to find angleangledihedral data for 604 610 719 610
Unable to find torsion data for 100 604 610 719
Unable to find endbonddihedral data for 100 604 610 719
Unable to find midbonddihedral data for 100 604 610 719
Unable to find angledihedral data for 100 604 610 719
Unable to find angleangledihedral data for 100 604 610 719
Unable to find torsion data for 101 618 803 107
Unable to find endbonddihedral data for 101 618 803 107
Unable to find midbonddihedral data for 101 618 803 107
Unable to find angledihedral data for 101 618 803 107
Unable to find angleangledihedral data for 101 618 803 107
Unable to find oop data for 605 601 1606 600
Unable to find oop data for 604 708 610 610
Unable to find oop data for 604 610 708 719
Unable to find oop data for 100 610 610 719
Unable to find angleangle data for 605 605 601 100
Unable to find angleangle data for 605 601 1606 100
Unable to find angleangle data for 605 601 1606 600
Unable to find angleangle data for 601 600 600 600
Unable to find angleangle data for 600 600 600 807
Unable to find angleangle data for 604 708 610 610
Unable to find angleangle data for 604 610 708 719
Unable to find angleangle data for 100 610 708 610
Unable to find angleangle data for 100 610 610 719
"

and much more than that? Is the problem in the forcefield itself ? Is it advisable to use another forcefield that resolves all of those issue?

Please any advice on that would be highly appreciated.

thanks

Elie Moukaes
Niversity of Notts
NG7 WRD
UK

2

Dear Elie,
Please take a look at your force field file. You did not specified the parameters that have been mentioned in the warning messages including some dihedral and angle terms, etc. Please follow the instructions carefully and then try to run the script again. Let me know if you have additional problems.

3

Thanks a lot for your reply. I am aware of those missing parameters. some parameters are missing even for the HCl molecule. Any source from where I can get information about bond date for example to fill in those gaps? or any other solution to circumvent this problem?

Thanks

Elie

4

Dear Elie,
You need to find the related articles that have mentioned HCl as their force field. It is a matter of searching the articles. I think several force fields are available in open literature and you could easily find them. After finding the parameters, you need to run msi2lmp_gcc32.exe to convert from a .car (msi) material studio file to lammps data file. Please be careful about the format of the previous force fields such as charmm, pcff, cvff, etc in the accelrys software.

Good luck,