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[lammps-users] How to make a supercooled liquid by LAMMPS
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[lammps-users] How to make a supercooled liquid by LAMMPS


From: bahman daneshian <bahmanpbamp@...24...>
Date: Tue, 29 Aug 2017 15:22:28 +0430

Dear Lammpsers, 

I would like to have a supercooled melt at 1156K. 

As you can see below, I used fix temp/rescale for fast cooling of the system and then let  the system a 7000 time steps to reach to  equilibrium under NVT ensemble .
 But, when I plot the potential energy versus time curve, I cannot see a non-equilibrium condition at the beginning of potential energy curve which indicating to the initial non equilibrium condition.it meen that I couldnot access to the supercooled melt. 

So, any helpful comment  is highly appreciated. 



#Phase 1 ------------------------------------------Simulation main setup----------------------------------
dimension      3
units   metal               # if you select units metal, distance are based on Ang
atom_style     atomic
boundary       p p p               # if you select dimension2, you have to select boundary as ppp.
lattice        fcc  3.6150        #3.6147 is Cu unit cell size in Ang as per units metal


#simulation box is simulbox 
region simulbox block 0 10  0 10 0 10 #units box                  
create_box   2 simulbox   #2 is number of atoms types
create_atoms 1 box
mass     1  63.550 #mass must always be defined after create_box
mass     2 63.550


velocity all create 300 300
pair_style eam #You can use an alloy EAM file for just a single element.
pair_coeff * * Cu_u3.eam
neighbor 2.5 bin
neigh_modify every 20 delay 0 check no

fix 1 all npt temp 1375.0 1375.0 0.01 iso 1.01325 1.01325 1.01325   # Cu melting point 1358K
thermo 100
dump  1 all image 500 image.*.png  type  type  adiam 1.5 axes yes 0.8 0.02 zoom 1.0 view 80 -30
dump_modify 1 backcolor white boxcolor white acolor 1*2 blue/red/orange/green/cyan/aqua/yellow/red
run 100
unfix 1


fix 2 all temp/rescale 100 1375 1156 0.02 1.0
run 1000

fix 3 all nvt temp 1156.0 1156.0 0.01 # Tdamp must be 100 timetep =100*0.001=0.1
thermo 100
dump  3 all image 500 image.*.png  type  type  adiam 1.5 axes yes 0.8 0.02 zoom 1.0 view 80 -30
dump_modify 3 backcolor white boxcolor white acolor 1*2 blue/red/orange/green/cyan/aqua/yellow/red
run 5000
unfix 3


Regards,
B. D