MANYBODY hybrid potential

Dear LAMMPS Users,

I am trying to mix different potentials in order to describe the interaction of a silicon tip with an alumina surface.

I chose to adopt potentials belonging to MANYBODY group, since they are suitable for this kind of application and it looks like they can be mixed without losing the physical meaning of the simulation. Please correct me if I am wrong.

The interaction between Al and Si is described by the MEAM potential Jelinek_2012_meam_alsimgcufe, while the interactions between Si O and Al O are described, respectively, by the SiO.1997.vashishta file and an equivalent file containing the parameters for Al and O, which have been found in a paper by the same author.

I am using the command hybrid/overlay in order to add the contributions coming from every potential to the final definition of the forces on the atoms.

I noticed that the parameters describing the forces between O-O are different in the Si-O and the Al-O vashishta potentials and I would like to be sure to avoid the addition of meaningless contribution to the hybrid potential.

In my opinion, I should keep the O-O interaction parameters coming from alumina sourcefile and set to zero the contribution from SiO.1997.vashishta file, since it should be applied to oxygen atoms in silica, which is not present.

Following the same principle and considering that meam potential embeds the Al-Al and Si-Si interactions, I should not consider the contributions for the same couples coming from the vashishta potential, avoiding the application of a double interaction between the same couples of atoms.

I will be grateful if someone more expert than me comments my statements and corrects me if I am wrong.

Kind regards

Andrea Mio, PhD

DIA – Dipartimento di Ingegneria e Architettura

Università degli studi di Trieste