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Re: [lammps-users] temp doesnt increase during equilibration
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Re: [lammps-users] temp doesnt increase during equilibration


From: Stefan Paquay <stefanpaquay@...24...>
Date: Thu, 24 Aug 2017 11:36:11 -0400

I'm thinking that it is a problem with your temperature time constant. Nosé-Hoover thermostats can take a long time to equilibrate. Try reducing the time constant to something smaller.

On Thu, Aug 24, 2017 at 5:53 AM, Meral Sharkas via lammps-users <lammps-users@lists.sourceforge.net> wrote:
Dear team,

I am trying to equilibrate my system at 300 k and 0 bar, my system is starting at high pressure so I relaxed my box at 0 k and used nve/lim to control the pressure. When I tried to raise the temperature to 300 k I found that the max temp reached was 30 k. May I ask what would be the reason for that?

Thank you in advance.

Thank you Stefan for your help. 

so how can i know if there are atoms not moving?


#                                                  ****System identification**** 


units         metal
atom_style    charge
boundary      p p p
#read_data     data.cryst
#replicate     2 2 2  




lattice custom 1 a1 6.607 0 0 a2 0 6.607 0 a3 0 0 5.982 basis 0.0 0.75 0.125 basis 0.0 0.25 0.875 basis 0.5 0.75 0.375 basis 0.5 0.25 0.625 basis 0.0 0.75 0.625 basis 0.0 0.25 0.375 basis 0.5 0.75 0.875 basis 0.5 0.25 0.125 basis 0.0 0.0658 0.1955 basis 0.0 0.9342 0.8045 basis 0.5  0.0658 0.3045 basis 0.5 0.9342 0.6955 basis 0.0 0.5658 0.8045 basis 0.0 0.4342 0.1955 basis 0.5 0.5658 0.6955 basis 0.5 0.4342 0.3045 basis 0.6842 0.25 0.9455 basis 0.8158 0.75 0.4455 basis 0.8158 0.25 0.5545 basis 0.6842 0.75 0.0545 basis 0.1842 0.25 0.5545 basis 0.3158 0.75 0.0545 basis 0.3158 0.25 0.9455 basis 0.1842 0.75 0.4455 

region R1 block -1 1 -1 1 -1 1

create_box    3 R1
 

create_atoms 3 region R1 basis 1 1 basis 2 1 basis 3 1 basis 4 1 basis 5 2 basis 6 2 basis 7 2 basis 8 2 basis 9 3 basis 10 3 basis 11 3 basis 12 3 basis 13 3 basis 14 3 basis 15 3 basis 16 3 basis 17 3 basis 18 3 basis 19 3 #basis 20 3 basis 21 3 basis 22 3 basis 23 3 basis 24 3



mass          1 91.224
mass          2 28
mass          3 16
group         1 type 1   # zircon
group         2 type 2   # silicon
group         3 type 3   # oxygen

set group     1 type 1 charge 3.8
set group     2 type 2 charge  2.0
set group     3 type 3 charge -1.45

velocity      all create 1 7928459 dist gaussian

dump atom     all custom 1000 dump.coordinates id type x y z 

#                                               ****System interatomic potential****

kspace_style ewald 5e-3

pair_style born/coul/long 10

#pair_style hybrid/overlay table linear 9999 ewald coul/long 10 


pair_coeff 1 3   1967.0 0.305004 0.0 0.0 0.0 
pair_coeff 2 3   1277.0 0.227225 0.0 0.0 0.0  
pair_coeff 3 3   1755.0 0.306820 0.0 0.0 0.0  
pair_coeff 1 2   0.0 0.306820 0.0 0.0 0.0  
pair_coeff 2 2   0.0 0.306820 0.0 0.0 0.0  
pair_coeff 1 1   0.0 0.306820 0.0 0.0 0.0   

timestep 0.001
thermo 100

compute me all pressure thermo_temp
thermo_style custom step atoms temp press c_me vol lx ly lz density 


fix 1 all nve
run 1000
unfix 1

fix 1 all nve/limit 1
run 1000
unfix 1     


fix 2 all nve/limit 0.8
run 1000

unfix 2 

fix 3 all nve/limit 0.6
run 1000
unfix 3

fix 4 all nve/limit 0.4
run 1000    
unfix 4

fix 1 all nve/limit 0.2
run 1000    
unfix 1    

fix 1 all nve/limit 0.1
run 1000    
unfix 1    

fix 1 all nve/limit 0.07
run 1000    
unfix 1    


fix 1 all nve/limit 0.04
run 1000    
unfix 1
    
    
fix 1 all nve/limit 0.02
run 1000    
unfix 1    

fix 1 all nve/limit 0.01
run 1000    
unfix 1    


fix 1 all box/relax iso 0.0

min_style cg
minimize 1e-25 1e-25 5000 100000

run 100
unfix 1

#Equilibration
fix                     2 all npt temp 1 300.0 100 iso 0.0 0.0 1000
run 100000



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