[lammps-users] high order derivatives of atom position

Hi, I am wondering whether the Lammps stores high order derivatives of atom position. The first order derivatives should be velocity, and the second order derivatives are acceleration. But could I get information about third order or fourth order derivatives? Many thanks.

Regards,
Liang Chen

Hi, I am wondering whether the Lammps stores high order derivatives of atom
position. The first order derivatives should be velocity, and the second
order derivatives are acceleration. But could I get information about third
order or fourth order derivatives? Many thanks.

no. they are never computed. please keep in mind that
lammps uses a verlet integrator which is a second order
PDE solver with a forth order error, if i am not mistaken.

you would either have to write a fix to do a numerical derivative
from the existing position/velocity/forces information and its history,
or dump position/velocity/forces to a file and post process.

cheers,
   axel.