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Re: [lammps-users] question about melting point
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Re: [lammps-users] question about melting point


From: Jan Fikar <fikar@...6994...>
Date: Fri, 27 Apr 2018 15:29:10 +0200

How does your sample look like? Typically you need half box FCC and half
box random arrangement with the same density - i.e. amorphous liquid like.

Then you run for long time at a constant temperature and observe if the
FCC is slowly growing or shrinking. It tells you, if the temperature is
below or above the melting point, you are looking for.

On 04/27/2018 03:20 PM, ehsan gowdini wrote:
> Dear all friend
> 
> I want to calculate Gold melting point and I use EAM potential and this script :
> 
> units         metal
> dimension     3
> boundary      p p p
> atom_style    atomic
> atom_modify   map array
> 
> 
> # ---------- Create Atoms ---------------------
> 
> read_data       Au256.data
> 
> 
> # ---------- Define Interatomic Potential ---------------------
> pair_style eam
> pair_coeff * * Au_u3.eam
> neighbor 2.0 bin
> neigh_modify delay 10 check yes
> 
> # ---------- Define Settings ---------------------
> 
> compute eng all pe/atom
> compute eatoms all reduce sum c_eng
> 
> # ---------- Run Minimization ---------------------
> 
> reset_timestep    0
> fix               1 all box/relax iso 0.0 vmax 0.001
> thermo            10000
> min_style         cg
> minimize          1e-25 1e-25 5000 10000
> 
> 
> #-----------------dynamic run in new temperature
> 
> dump                 npt all xyz 5000 ionized-npt.xyz
> 
> velocity             all create 100 45827325 mom yes rot yes dist uniform
> 
> fix                  npt1 all npt temp 100.0 2000.0 0.01 y 1.0 1.0 500
> fix                  2 all momentum 10 linear 1 1 1 angular
> fix                  3 all recenter INIT INIT INIT units box
> 
> thermo_style         multi
> 
> timestep             0.001
> 
> run                  1000000
> unfix                npt1
> 
> undump               npt
> 
> 
> 
> the gold structure is FCC and it has 256 atom
> 
> 
> after run I draw potential energy v.s temperature curve but I see no
> any jump in curve that show transition phase
> 
> I search in mailing list but i no find any thing
> 
> what is your suggestion?
> 
> best
> 
> Ehsan
> 
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