Hi,all.
I want to relax and equilibrate graphene on a SiO2 substrate. I refer to the following paper, but the average distance between graphene and SiO2 substrate does not match the paper.
Is there anything wrong with my file?
Wang, Weidong, et al. "Relaxation properties of single layer graphene on SiO2 substrate." *Journal of nanoscience and nanotechnology* 15.4 (2015): 2970-2975.
Thank you in advance.
Rasty.
log LOG/log_in.txt
units metal
dimension 3
atom_style molecular
boundary p p p
timestep 0.001
newton on
read_data forlammpsGS0119.dat #GS2
group mobile type 1
read_data forlammpsSiO0203.dat add append offset 1 0 0 0 0 shift 7.9385 2.4493 -14.009
group Si type 2
group O type 3
group SiO type 2 3
pair_style hybrid airebo 3.0 tersoff lj/cut 2.5
pair_coeff * * airebo CH.airebo C NULL NULL
pair_coeff * * tersoff Tersoff NULL Si O
pair_coeff 1 3 lj/cut 0.006734 3.275
pair_coeff 1 2 lj/cut 0.008890 3.628
neighbor 2.0 bin
neigh_modify delay 0 every 1 check yes
dump 1 all custom 100 dump/step-*.lammpstrj id type x y z vx vy vz fx fy fz
thermo_style custom step temp press ke pe etotal press time
thermo 100
min_style cg
minimize 1.0e-10 1.0e-17 10000 100000
velocity all create 1 208040 dist gaussian
fix nvt mobile nvt temp 0.01 0.01 0.001
fix nvt2 SiO nvt temp 0.01 0.01 0.001
run_style verlet
run 60000
unfix nvt
unfix nvt2
Are your choice of force field and potential parameters the same as in the publication?
That would be the be the most likely cause for differences.
Didn’t I already comment on your unusual choice of LJ cutoff previously?
What is the point of running MD at 0.01 K?
Axel.
Thanks,Axel.
Yes. I asked a question. I received the following response.
(your cutoff of the lj/cut interaction looks very short for the choice of parameters (it cuts of before the minimum) and more if you used cut and paste from an input using reduced units instead of metal units. )
Unless I misunderstand how to use the command, I feel that the parameters and force field settings are the same as in the publication. The reason for setting it to 0.01K is to minimize the fluctuation of graphene.
Rasty.
2021年2月4日(木) 20:01 Axel Kohlmeyer <[email protected]>:
Thanks,Axel.
Yes. I asked a question. I received the following response.
(your cutoff of the lj/cut interaction looks very short for the choice of parameters (it cuts of before the minimum) and more if you used cut and paste from an input using reduced units instead of metal units. )
Unless I misunderstand how to use the command, I feel that the parameters and force field settings are the same as in the publication. The reason for setting it to 0.01K is to minimize the fluctuation of graphene.
how you feel is your thing, but I am just saying that neither of the two choices makes much sense to me. that is not just a feeling, but there is physical reasoning behind that:
a) if you have a cutoff at the potential minimum or shorter of an LJ potential, then there is no attraction, ever. and you may get a large jump in forces and energies if an atom comes close to another and the force (and interaction energy) jumps from zero to strongly repulsive.
b) if you run at an ultra low temperature (and for a rather short trajectory) then there is not much energy that makes the particles move. and since you cut off all attraction the only way the graphene will eventually move is away from the surface.
you have the publication in front of you and you can replace feeling with fact. I doubt that you can find confirmation for either setting. but that is up to you to figure out.
axel.
Thanks, Axel.
It is very difficult for me to reax graphene on SiO2.
I will accept your advice and work hard.
I have another question.
why should graphene be placed on SiO2 substrate?
Is there any reason other than fixing graphene?
2021年2月5日(金) 7:16 Axel Kohlmeyer <[email protected]>:
I don’t understand the question. Please elaborate.