Dear all,
Thany you for your attention. I have some questions about the TAD when I simualted with it.
Firstly, I want to know how to estimate the correct of results obtained from MD&TAD.
Secondly, in the process of simulation, the E may become zero in sometime, I don’t whether this situation is wrong or not? but when I reset the parameters of NEB, those energy will become some positive value.
Thirdly, I want to know whether the initial configuration of system in TAD simulation is the configuration of system in the MD simulation, for example, when I introduced a vacancy into the perfect SiC, after the MD relaxed at high temperature, the configuration may become very disorder, but I am very surprised that the initial TAD configuration did not change a lot when compared with the unrelaxed MD configuration.
Here is my in.file
temperature accelerated dynamics model for vacancy clusters in sic
events occur when a neighboring atom diffuses to the vacant site
run this on multiple partitions as
mpirun -np 4 /lmp -partition 4x1 -in in.sic
change the etol from 0 to 0.0001
units metal # sets units to ‘metal’ units - Atomic units w/ ps timescale
atom_style atomic
atom_modify map array sort 0 0.0
boundary p p p
neighbor 2.0 bin # sets maximum neighbor search radius to cutoff value, using bin-sort algorithm
neigh_modify delay 0 every 10 check yes #one 10000 page 100000 # checks if neighbor list should be rebuilt after and every 5 steps
Create geometry using internal stuff
lattice diamond 4.3765
read_data data.sic
mass 1 12.0107 # type 1 = C
mass 2 28.0855 # type 2 = Si
dump 0 all custom 1 dump.init id type xu yu zu
run 0
undump 0
temperatures and velocity
variable tlo equal 2000.0
variable thi equal 2500.0
velocity all create ${thi} 52872745 mom yes rot yes dist gaussian units box
minimization parameters
variable etol equal 1.0e-5
variable ftol equal 1.0e-5
variable maxiter equal 10000
variable maxeval equal 10000
variable dmax equal 1.0e-1
Define potential
pair_style tersoff/zbl
pair_coeff * * SiC.tersoff.zbl C Si
timestep 0.0001
variable T equal elapsed*dt
#run the system dynamicaly
fix 1 all nve
fix 2 all langevin {thi} {thi} 0.0001 6994835 zero yes
thermo 100
thermo_style custom v_T elapsed dt step temp pe etotal press
dump 1 all custom 100 dump.start id type xu yu zu
run 10000
undump 1
Eliminate COM motion
velocity all zero linear
thermo_style custom v_T elapsed dt step temp pe etotal press
dump events all custom 1 dump.sic id type xu yu zu
compute event all event/displace 1.0 #one half of the first nearest neighbor
unfix 1
unfix 2
fix 1 all nvt temp {thi} {thi} 0.001
tad nsteps nevent tlo thi delta_conf tmax compute
[min etol ftol niter neval]
[neb etol_neb ftol_neb n1steps n2steps nevery]
[min_style min_style]
[neb_style min_style]
[neb_log logfile]
tad 1000000 10 {tlo} {thi} 0.05 1 event &
min {etol} {ftol} {maxiter} {maxeval} &
neb 1.0e-12 0.0 10000000 10000 20 &
min_style cg &
neb_style fire &
neb_log log.neb
Therefore, I hope you can give me some suggestions about this TAD method. Thank you very much!