I have recently been reading these two books: “Understanding Molecular Simulation” and “The Art of Molecular Dynamics”, they’re both great but I feel like they don’t cover everything that GULP can do.
For example GULP’s minimiser is significantly better than the one in LAMMPS, why is that? Are there any other references out there beyond the main papers of GULP which explain this well?
Please chime in with any suggestions for books, papers, or videos, and hopefully we can compile a decent list of useful references!
Hi Connor. I can explain why GULP’s minimiser is better than that in LAMMPS here - it’s because is a lattice dynamics code (primarily) and so uses second derivatives, whereas LAMMPS is an MD code and only has first derivatives. Having the Hessian makes a big difference to the convergence rate if the system is in the harmonic region. In theory this could decrease the number of steps from N (1st derivatives only) to 1 (2nd derivatives). This would be the extreme case of course & reality is more subtle. The thing to look up is Newton-Raphson optimisation & I think this is covered in the GULP paper (Mol. Simul.) and books such as the one by Andrew Leach.