I am working on forsterite (MgSiO4) to find out its mechanical properties (like stress strain relationship). I used VMD to create data files and later defined forcefields without any problem. In data file, I see that the atoms were in fixed place. But, after minimization, I found that the atoms are behaving (moving) like a liquid, but not like a metal. I have found from the mailist that I can create lattice before loading the read_data file for the molecules. But, I want to know, would I have to mention default create_atoms command again for creating the molecules of forsterite since I already have and defined a data file for forsterite in the lammps script? Is it possible to place the molecules or atoms of from the data files to the lattice box?
MS Student, Virginia Tech
Why should a crystalline material behave like a metal?
If the structure you have input is not stable while it should be, then there is likely a problem with either your geometry or your force field parameters or force field and topology assignments.
Of course not.
This statement makes no sense. The lattice command in LAMMPS has no physical meaning, it is merely a tool for computing positions, so that atoms (or molecules) can be created at those positions. Since you already have explicit positions in your data file, you do not need a lattice.
Thank you sir for your clarification.