A hybrid potential "Tersoff+ILP" for the homo- and heterostructures of graphene and hBN

[BBBuZHIDAO]

Summary

This PR adds a hybrid potential, combining Tersoff (1988) potential and interlayer potential (ILP), for graphene, h-BN and their heterostructures. The intra- and interlayer interactions are described by Tersoff potential and ILP potential, respectively. Similar to PR #951, this hybrid potential use a group method to identify different layers, too.

Modification

• Add ilp_tersoff.cu and ilp_tersoff.cuh files to compute the energy, force and virial.
• Add a check statement in force.cu file for this hybrid potential.
• Add two example potential files.

Usage

• In run.in file, the definition of potential needs two potential files: the first for ILP potential and the next for Tersoff potential.

potential ./hybrid_tersoff_ilp_gr_hbn_ILP_oywg_2018.txt ./hybrid_tersoff_ilp_gr_hbn_Tersoff_Kinaci_2012.txt

• In the potential file for ILP, the second line is used to define the group method for different layers. For example,

tersoff_ilp 3 B C N
0

the 0 means the groups set in group method 0 are defined as different layers.

• The element orders in the Tersoff potential file must be the same as the ILP. Note that there is no head line for element list in the Tersoff potential file. The Tersoff parameters orders are the same as previous Tersoff 1988 potential in GPUMD.

Test

The test model is a gr/h-BN heterostructure with 1,600 atoms.

1. Compare with LAMMPS (run 0)
   

2. Energy conservation
   

3. DEBUG flag test
   

Others

If any questions, please feel free to let me know!