[lammps-users] WARNING: Mixing forced for lj coefficients

Dear all,

I 've used kspace_style Ewald/n with pair_style lj_coul for long-ranged interactions and when my simulation starts, I get this message: WARNING: Mixing forced for lj coefficients. What does it means? I don’t find any explanation at the site of LAMMPS or in the manual.

Yours faithfully,

Giannis

2010/10/21 Giannis Mathioudakis <[email protected]…8…>

Dear all,

I 've used kspace_style Ewald/n with pair_style lj_coul for long-ranged interactions and when my simulation starts, I get this message: WARNING: Mixing forced for lj coefficients. What does it means? I don’t find any explanation at the site of LAMMPS or in the manual.

Hello, Giannis:

This is a warning, as opposed to an error. The issue is that the ewald/n package needs to have values for all LJ pairs that it needs to work with. If the user doesn’t specify them, the code has to produce them via mixing rules. That’s what the message is telling you.

–AEI

I’ve used mixing rule (arithmetic) for my lj pairs which are in data file of my simulation. If I don’t use Ewald/n for long-ranged interactions, I don’t have this warning message.

Giannis

2010/10/21 Giannis Mathioudakis <[email protected]…8…>

I’ve used mixing rule (arithmetic) for my lj pairs which are in data file of my simulation. If I don’t use Ewald/n for long-ranged interactions, I don’t have this warning message.

Alexi:

That’s because the message is specific to pair style lj/coul; the warning is not included in other pair styles, and hence you won’t get it.

However, I believe that the other pair styles that support mixing will use it if you don’t specify the coefficients for all of the i, j pairs you want to use with that style. (See the manual on pair_modify for more about this.)

–AEI

This pair style is in a "user" package which means
a user wrote and maintains it. The error/warning
messages from such packages are not included in the LAMMPS
manual. You can contact the author directly if
you're still worried, but Ahmed's comments are correct.
The warning just means the pair style is going to
do some mixing.

Steve

2010/10/21 Giannis Mathioudakis <[email protected]>: