ewald/disp vs ewald/n

Hi everyone,

I am trying to reproduce a mean square displacement calculation carried out by a previous student in our group. This calculation was performed with an older version of lammps using the ewald/n kspace_style and buck/coul/long pair style.

When I try to perform the same calculation with “ewald/disp” I get much higher mean square displacement values. I tried both the buck/coul/long and the buck/long/coul/long pair_styles.

It would be great if someone could give me some ideas as to what kspace_style – pair_style combination I should use to obtain similar results. The input file is below.

Prateek

LiLaZrO garnet

Initiation

units metal
atom_style charge
boundary p p p
read_data LLZ.data

Atom definition

group La type 1
group Zr type 2
group O type 3
group Li type 4
set group La charge 3.00
mass 1 138.91
set group Zr charge 4.00
mass 2 91.224
set group O charge -2.00
mass 3 15.999
set group Li charge 1.00
mass 4 6.941

Interatomic potential

kspace_style ewald/n 1.0e-5
pair_style buck/coul/long 8.0

pair_coeff * * 0.00 0.100000 0.000000
pair_coeff 1 3 5436.827 0.293900 0.000000
pair_coeff 2 3 7290.347 0.261000 0.000000
pair_coeff 3 3 25.410 0.693700 32.320000
pair_coeff 3 4 426.480 0.300000 0.000000

Simulation parameters (set Tdamp~30-50 for T < 500 K)

fix 1 all nvt temp 1700 1700 100
compute msd all msd
compute msdLi 4 msd
compute msdLa 1 msd
compute msdZr 2 msd
compute msdO 3 msd

thermo 200
thermo_style custom step time temp press px py pz pe ke etotal c_msd c_msdLi c_msdLa c_msdZr c_msdO
dump 1 all custom 200 xyz.dat id type x y z
dump 2 all custom 200 velocity.dat id type vx vy vz
dump 3 all custom 200 forces.dat id type fx fy fz

Run simulation (dt = 1 fs, t = 10 ns)

timestep 0.001
run 10000