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[lammps-users] zero barrier from NEB calculations
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[lammps-users] zero barrier from NEB calculations


From: anyy zsj <zsjanyy@...16...>
Date: Wed, 19 Jul 2017 18:33:47 +0000 (UTC)

Dear lammps users:

I have a question about minimization implemented in lammps. I have a defective configuration with an interstitial and a vacancy in it. After I relax it with minimization command using either cg or sd method, the defect pair finds an optimal location. Then I use NEB calculations to calculate the barrier when moving the interstitial to the vacancy. However, I always get a zero barrier like this:

3156 9.9485711e-09 7.6750495e-10 4.5723397e-12 9.9485711e-09 4.5723397e-12            0    5.4487092    3.8110102            0   -16642.612  0.066666667   -16642.655   0.13333333   -16642.906          0.2   -16643.173   0.26666667   -16643.483   0.33333333   -16643.992          0.4   -16644.533   0.46666667   -16645.057   0.53333333   -16645.579          0.6   -16646.098   0.66666667   -16646.641   0.73333333   -16647.232          0.8   -16647.695   0.86666667   -16647.951   0.93333333   -16648.046            1   -16648.061
 
I have tried all kinds of convergence criteria during minimization but the configuration seems stable. So why there is 0 barrier but the system cannot relax to the low energy state? Does it make sense in reality?
 
Thank you very much!