[gmx-users] Shifting in Verlet cut-off schemes?

[Yun Shi]

Hi all,

I have read http://www.gromacs.org/Documentation/Cut-off_schemes, but
still unsure about how Verlet works.

"The group cut-off scheme can be combined with a buffered
pair-list......The Verlet list scheme has buffered neighborlists with
exact cut-off's". What does "buffered neighborlists" mean? Including
neighbors beyond the cutoff distance (e.g. 1.0 nm)? Then what is the
delta-distance for this buffer region?

"LJ and Coulomb potential are by default shifted to zero by
subtracting the value at the cut-off". Does the program only do such
subtractions at exactly the cutoff distance? Or does it shift both
potential functions throughout the entire distance range (e.g. from 0
to 1.0 nm)?

Then would this cause potential problems since some force fields are
not parametrized with a shifting approach?

Thanks,
Yun