Collision of molecule with surface?

[cchang]

Hi,

I would like to calculate the initial dynamics of a molecule colliding with a surface. I'm confused about the SMASS options, though. I've set initial velocities in the POSCAR file, but running SMASS=-3, they appear to be reset (i.e., the molecule vibrates but does not move relative to the surface, which it should given the velocities set in POSCAR).
The documentation for the SMASS=-2 option indicates that initial velocities will be read in, but that they will be held constant, which will create problems once nuclei start to overlap, and energies spike.
What I'm looking for is velocities initialized from POSCAR, but then adjusted according to the forces experienced in the simulation for either constant energy, or constant temperature. I've got

Code: Select all

NSW?=1000?;?ISIF=0?;?IBRION=0
POTIM=0.67
SMASS=-3

, but what should I have?

Thanks

[support_vasp]

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