vashishta hybrid

Hi all,

I am trying to use hybrid style to simulate quartz. Type 1 Si atoms are modeled by meam, type 2 Si and type 1 O atoms are modeled by vashishta. I tried different pair_coeff command with vashishta but I always got the following error.

pair_style hybrid vashishta meam
pair_coeff * * SiO.1997.vashishta NULL Si O

pair_coeff * * meam lee_m.meam Si Si_lee_m.meam Si NULL NULL

ERROR: Pair coeff for hybrid has invalid style (…/pair_hybrid.cpp:420)
Last command: pair_coeff * * SiO.1997.vashishta NULL Si O

This command also didn’t work: pair_coeff 2 3 SiO.1997.vashishta Si O . The Vashishta potential used is from potential folder of lammps-7Aug19. Any suggestions would be appreciated.

Thank you,

the pair_coeff for hybrid requires to provide the pair style name that the coeffs are applied to. you did it correctly for the meam substyle, but not for the vashishta substyle.

the pair_coeff 2 3 … line cannot work for the same reason, but also because you must use pair_coeff * * for most manybody pair styles including vashsishta.

… and you have one more problem that wasn’t reported because of the syntax errors.
you need to provide a pair style that defines the interactions between types 1 and 2/3. this cannot be represented with a manybody pair style but must be a pair-wise additive pair style.

please also note that there are plenty of discussions in the mailing list archives, which are proper systems, where you can use manybody with hybrid and where you would be better off to have a single parameterization and a single pair style for all atoms.


Hi Axel,

Thank you for your reply and pointing out the extra problems. It’s very helpful. I have found the post you mentioned in the mailing list with the right keyword.