kspace style

LAMMPS LAMMPS Mailing List Mirror
1

Dear lammps-users
I want to model a system(mix Methanol and water). Here I use tip4p water model. We know the kspace_style of tip4p model is pppm/tip4p 0.0001. But if we simulate a mixing system.How should we use the kspace_style ? Do we still use pppm/tip4p 0.0001?
Thanks!
Jack zhuang

2

Dear lammps-users
I want to model a system(mix Methanol and water). Here I use tip4p water model. We know the kspace_style of tip4p model is pppm/tip4p 0.0001. But if we simulate a mixing system.How should we use the kspace_style ? Do we still use pppm/tip4p 0.0001?

Sure, why not? Please have a closer look at the manual.

3

All that pppm/tip4p is doing, beyond regular pppm is

identifying water molecules and adding a 4th site for the

long-range calculation. It will work whether your system
is all water or water added to some other charged molecules.

Steve

4

Thanks!
Then if I can also think that the pair_style lj/cut/tip4p/long will including the function of lj/cut/coul/long ?
I can only use lj/cut/tip4p/long instead of lj/cut/coul/long?

Jack zhuang

5

Thanks!
Then if I can also think that the pair_style lj/cut/tip4p/long will
including the function of lj/cut/coul/long ?
I can only use lj/cut/tip4p/long instead of lj/cut/coul/long?

Sure, why not? Please have a closer look at the manual (again!).

6

Thank you for your patient reply!
But I dont know why my error still occurred. I want to simulate the mixing system (incuding tip4p model)

example 1(mixing system)

pair_style lj/charmm/coul/long 8 9 9
kspace_style pppm/tip4p 0.0001

error: KSpace style is incompatible with Pair style (…/kspace.cpp:174)

example 2(mixing system)

pair_style lj/cut/tip4p/long 33 34 32 54 0.15 8.5 8.5
kspace_style pppm/tip4p 0.0001

here my water model : Ostyle is 33, Hstyle is 34 bond style is 32 angle style is 54
error:Incorrect args for pair coefficients (…/pair_lj_cut_coul_long.cpp:622)
example 3(mixing system)
but if I dont use the tip4p water model

pair_style lj/charmm/coul/long 8 9 9
kspace_style pppm 0.0001

it can run without error.

Thanks !
Jack zhuang

7

Thank you for your patient reply!
But I dont know why my error still occurred. I want to simulate the mixing
system (incuding tip4p model)

example 1(mixing system)
pair_style lj/charmm/coul/long 8 9 9
kspace_style pppm/tip4p 0.0001
error: KSpace style is incompatible with Pair style (../kspace.cpp:174)

this is obviously incorrect.

example 2(mixing system)
pair_style lj/cut/tip4p/long 33 34 32 54 0.15 8.5 8.5
kspace_style pppm/tip4p 0.0001

the seems correct.

here my water model : Ostyle is 33, Hstyle is 34 bond style is 32 angle
style is 54
error:Incorrect args for pair coefficients
(../pair_lj_cut_coul_long.cpp:622)

if you look at this error message, you'll see that it is about pair
*coefficients* and not pair *style*, so it is caused by the pair_coeff
line.

example 3(mixing system)
but if I dont use the tip4p water model
pair_style lj/charmm/coul/long 8 9 9
kspace_style pppm 0.0001
it can run without error.

and if you would write a correct input script, and followed the
suggestions in the manual how to debug input scripts, you would have
found the issue and have been able to run long ago.

axel.