table pair style

Dear lammps users,

I want to check if LJ table potential can reproduce analytic potential results, so I get table.txt by the following scripts:

Pair_style lj/cut 2.5
Pair_coeff * * 1.0 1.0 2.5

Pair_write 1 1 5000 r 0.5 2 table.txt LJ

But when I use this table potential via

Pair_style table linear 5000
Pair_coeff * * table.txt LJ

There is a warning massage:

WARNING: 1 of 5000 force values in table are inconsistent with -dE/dr.

Why is the force values inconsistent with -dE/dr? the outer cutoff(2 A) is less than lj cutoff(2.5 A).

Thank you in advance.

Best wishes.

Lily

Dear lammps users,

I want to check if LJ table potential can reproduce analytic potential
results, so I get table.txt by the following scripts:

Pair_style lj/cut 2.5
Pair_coeff * * 1.0 1.0 2.5

Pair_write 1 1 5000 r 0.5 2 table.txt LJ

But when I use this table potential via

Pair_style table linear 5000
Pair_coeff * * table.txt LJ

There is a warning massage:

WARNING: 1 of 5000 force values in table are inconsistent with -dE/dr.

Why is the force values inconsistent with -dE/dr?

​because the test for -dE/dr fails at the minimum of the potential.
so the warning is to be expected. you should only worry, if there are more
than one points inconsistent.

axel.​