Hello everyone,
I am simulating Aluminum atoms on graphene monolayer system and I am using Lammps 14May-2016 version.
I have placed the monolayer of graphene below and the Al atoms on top of the graphene layer. I am using LJ 12-6 potential to model the interactions between carbon carbon atoms (type 2 atoms) in graphene, EAM potential to model the Al-AL (type 1 atoms) interactions and LJ 12-6 potential to model the interactions between C and Al atoms. I obtained the LJ parameter values of AL and C from this paper (http://www.nature.com/articles/ncomms12332) who used a similar approach. I found out the LJ parameter values for C-C atoms in graphene from this paper (https://arxiv.org/abs/1209.4248). The distribution of Al atoms on graphene is random and the initial distance between the graphene layer and AL atoms (assumed to be in the same plane initially) is 5 Angstorm.
When I am running the simulations, I am seeing that right when the minimisation process starts, the graphene atoms are moving up and covering the Al atoms entirely. Some Al atoms are even passing the carbon atoms of graphene and reaching the extreme bottom of the entire system. SO this obviously is wrong and not what I want.
I put aluminum and graphene atoms in separate groups and tried minimizing separately. Wasn’t sure if that helps. For example, I used the neighbour modify to exclude the group of graphene. But even then, some graphene atoms were moving in a random fashion.
I ran the simulations separately (only AL and only pure graphene) to check if I am using the correct potentials. The energy values of pure Aluminum actually matched the data produced in “Al99 relsease notes”(http://www.ctcms.nist.gov/potentials/Download/Al-YM/Al99_releaseNotes_1.pdf). Similarly pure graphene looked stable too.
As far as I understand, data file also looks right with correct formatting. I can visualise the entire stucture in the first frame of the simulation and then the trajectories are becoming erratic. Can someone please help me point out my error? Thank you so much. I am also attaching the files here and also pasting the Input file and the Log file below
INPUT SCRIPT
echo screen
dimension 3
boundary p p p
atom_style atomic
units metal
newton on
read_data data.AlonGNR
dump 1 all custom 500 releasedall_equilibrate.lammpstrj id type x y z
##SPECIFYING SEPARATE GROUPS
group aluminum type 1
group graphene type 2
#POTENTIAL FIX
pair_style hybrid eam/alloy lj/cut 15.0
pair_coeff * * eam/alloy Al99.eam.alloy Al NULL
pair_coeff 2 2 lj/cut 0.002415 3.4
pair_coeff 1 2 lj/cut 0.0079 3.9495
timestep 0.0005
thermo 100
thermo_style custom step temp press vol pe ke etotal
neighbor 3.0 bin
neigh_modify delay 0 every 1 check yes
min_style cg
min_modify line quadratic
minimize 1.0e-20 1.0e-15 10000 1000000
LOG FILE
LAMMPS (14 May 2016)
echo screen
orthogonal box = (-300.5 -300.5 -300.5) to (300.5 300.5 300.5)
1 by 1 by 1 MPI processor grid
reading atoms …
1299 atoms
291 atoms in group aluminum
1008 atoms in group graphene
Neighbor list info …
3 neighbor list requests
update every 1 steps, delay 0 steps, check yes
max neighbors/atom: 2000, page size: 100000
master list distance cutoff = 18
ghost atom cutoff = 18
binsize = 9 -> bins = 67 67 67
Memory usage per processor = 6.00621 Mbytes
Memory usage per processor = 6.00621 Mbytes
Step Temp Press Volume PotEng KinEng TotEng
0 0 15113.579 2.170818e+08 510334.96 0 510334.96
100 0 19.685773 2.170818e+08 38.95888 0 38.95888
200 0 0.30271624 2.170818e+08 -787.89263 0 -787.89263
300 0 0.011315706 2.170818e+08 -827.28911 0 -827.28911
400 0 6.1657926e-05 2.170818e+08 -839.47905 0 -839.47905
500 0 -0.038462493 2.170818e+08 -845.86523 0 -845.86523
600 0 0.00042508389 2.170818e+08 -852.12929 0 -852.12929
700 0 -0.010537667 2.170818e+08 -853.72592 0 -853.72592
800 0 -0.051599009 2.170818e+08 -857.18755 0 -857.18755
900 0 -0.0069230993 2.170818e+08 -861.40817 0 -861.40817
1000 0 -0.0090800681 2.170818e+08 -862.27093 0 -862.27093
1100 0 -0.015262716 2.170818e+08 -863.37896 0 -863.37896
1200 0 -0.0019275283 2.170818e+08 -864.00519 0 -864.00519
1300 0 -0.0082502485 2.170818e+08 -864.42211 0 -864.42211
1400 0 -0.0024599201 2.170818e+08 -864.77653 0 -864.77653
1500 0 0.00077326942 2.170818e+08 -865.07196 0 -865.07196
1600 0 -0.0084424461 2.170818e+08 -865.52471 0 -865.52471
1700 0 -0.0040755565 2.170818e+08 -865.81634 0 -865.81634
1800 0 -0.0026693299 2.170818e+08 -866.0683 0 -866.0683
1900 0 -0.000277965 2.170818e+08 -866.36448 0 -866.36448
2000 0 -0.0048051979 2.170818e+08 -866.91167 0 -866.91167
2100 0 -0.0069152878 2.170818e+08 -867.17589 0 -867.17589
2200 0 -0.0026399524 2.170818e+08 -867.48576 0 -867.48576
2300 0 -0.0059410845 2.170818e+08 -867.77876 0 -867.77876
2400 0 -0.0061156298 2.170818e+08 -867.97923 0 -867.97923
2500 0 -0.0044131256 2.170818e+08 -868.1967 0 -868.1967
2600 0 0.00015939299 2.170818e+08 -868.57148 0 -868.57148
2700 0 -0.0037714053 2.170818e+08 -868.80394 0 -868.80394
2800 0 -0.0024767818 2.170818e+08 -869.02162 0 -869.02162
2900 0 -0.0033508961 2.170818e+08 -869.2763 0 -869.2763
3000 0 -0.0010463404 2.170818e+08 -869.44043 0 -869.44043
3100 0 0.0002039706 2.170818e+08 -869.56952 0 -869.56952
3200 0 -0.0033533033 2.170818e+08 -869.6708 0 -869.6708
3300 0 -0.00029285418 2.170818e+08 -869.77735 0 -869.77735
3400 0 -0.00022362094 2.170818e+08 -869.89767 0 -869.89767
3500 0 -0.0012978423 2.170818e+08 -870.03196 0 -870.03196
3600 0 0.00014285219 2.170818e+08 -870.12858 0 -870.12858
3700 0 8.5818685e-05 2.170818e+08 -870.16958 0 -870.16958
3800 0 -0.001689599 2.170818e+08 -870.19625 0 -870.19625
3900 0 -0.00047924173 2.170818e+08 -870.21572 0 -870.21572
4000 0 -0.00023710367 2.170818e+08 -870.23138 0 -870.23138
4100 0 -0.00040231348 2.170818e+08 -870.24488 0 -870.24488
4200 0 0.00013066863 2.170818e+08 -870.25642 0 -870.25642
4251 0 0.00032438999 2.170818e+08 -870.26287 0 -870.26287
Loop time of 54.8002 on 1 procs for 4251 steps with 1299 atoms
99.9% CPU use with 1 MPI tasks x no OpenMP threads
99.9% CPU use with 1 MPI tasks x no OpenMP threads
Minimization stats:
Stopping criterion = linesearch alpha is zero
Energy initial, next-to-last, final =
510334.957157 -870.262871486 -870.262871486
Force two-norm initial, final = 27659.1 0.0322006
Force max component initial, final = 2948.92 0.00757888
Final line search alpha, max atom move = 7.62939e-06 5.78222e-08
Iterations, force evaluations = 4251 8075
MPI task timing breakdown:
Section | min time | avg time | max time |%varavg| %total
in.equilibrate (1.22 KB)
data.AlonGNR (49.9 KB)