Hi All,
Recently I use lammps_local_package(https://cmrl.lab.uic.edu/lammps_hessian.html) to compute the Hessian matrix, howerver i can’t get a convergence value when i change the epsilon value(displacement value for the centeral finite difference method). For the command module: hessian group_ID epsilon etol ftol nsteps maxiter.
I have used the following two command:
hessian SIA 5.0e-6 1.0e-12 1.0e-12 10000 10000
hessian SIA 5.0e-8
Then i diagonalized the hessian.out file to get the eigenvalues and i found that the eigenvalues of these two matrics are very different. Then i have tried a smaller epsilon value but there is no convergence.
Besides my lammps version is lammps-12Dec18.
Thank you so much for your time and consideration.
Sincerely,
Yingzhao He