fix deposit temperature increases wildly

Dear all,

I’m using fix deposit to add atoms to a surface (wall/region surface), I found that after some steps, the temperature suddenly increases wildly from 300 K to more than 10000 K. No special operations between the two output steps. Does anyone have some ideas about this?

I attached a part of the log file and the input script:

Step CPU all_comt TotEng PotEng KinEng

520000 1107.9676 291.76786 -473.194 -548.63734 75.443335
522000 1122.0002 300.80863 -472.80752 -551.10175 78.294226
524000 1135.9185 297.39284 -474.82871 -552.54099 77.712276
526000 1149.7769 292.14102 -481.64981 -558.30706 76.657251
528000 1163.6012 304.01443 -485.56969 -565.73973 80.170043
530000 1178.7277 10792.857 224272.72 -599.41768 224872.13
532000 1198.0074 9736.5589 406839.83 -635.48005 407475.31
534000 1215.9096 10152.683 572681.6 -643.40895 573325
536000 1233.5887 10839.76 786197.92 -649.99146 786847.91
538000 1250.9888 11613.607 1067282.2 -653.95743 1067936.2
540000 1268.413 12365.14 1413949.6 -657.56018 1414607.2
542000 1285.9298 13069.8 1763506.4 -660.99865 1764167.4
544000 1303.4609 13821.006 2170217.6 -656.50805 2170874.2
546000 1320.943 14590.982 2647370.7 -656.55402 2648027.3
ERROR on proc 3: Particle on or inside surface of region used in fix wall/region (…/fix_wall_region.cpp:238)

compute all_comtemp all temp/com
compute_modify
​ ​
all_comtemp dynamic yes extra 0

fix 1 all nvt temp 300.0 300.0 0.5
fix_modify 1 temp all_comtemp
fix
​ ​
addwater all deposit 30000 1 200 2015 region slab near 3.0 vz -3.0 -3.0 units box

Best,

Wei Xiong

Dear all,

I'm using fix deposit to add atoms to a surface (wall/region surface), I
found that after some steps, the temperature suddenly increases wildly from
300 K to more than 10000 K. No special operations between the two output
steps. Does anyone have some ideas about this?

have you visualized the trajectory? does the temperature increase
correlate with the impact of a water molecule?
what is the assigned initial velocity of your water molecule (regard
the units setting!), what is your time step?
have you tried a shorter time step? or a slower initial velocity of
the deposited molecule? or both?

axel.

Axel, yes, I have tried smaller timestep from 5 fs to 1 fs, and smaller velocity from 30 to 3 A/ps. The same problem happens.

As you can see from my attached video (https://db.tt/oSi0GAnv), atoms seems suddenly being “freezed” at a certain step (during the process of fix deposit), the corresponding temperature increases fast from 300 K to 100000 K. Do you know what will be the problem?

I’ve attached the complete input script and the thermo output file.

input file:

processors 2 2 1
units metal
atom_style full
pair_style sw

read_data data.10

neigh_modify every 1 delay 0

pair_coeff * * mW.sw mW

region 0 block 1.0 319.32 1.0 319.32 -10.0 0.0 units box side out
fix wall0 all wall/region 0 lj93 {epsilon}e-3 2.5 20.0* *fix_modify wall0 energy yes* *region 1 cylinder z 11.44 11.44 5.0 0.1 50.0 units box side out* *fix wall1 all wall/region 1 lj93 {epsilon}e-3 2.5 20.0
fix_modify wall1 energy yes


compute all_comtemp all temp/partial 1 1 0

compute_modify all_comtemp dynamic yes extra 0

velocity all create 300.0 2014 rot yes dist gaussian

fix 1 all nvt temp 300.0 300.0 0.5
fix_modify 1 temp all_comtemp

dump 2 all custom 2000 all.lammpstrj id x y z
dump_modify 2 flush yes

timestep 1.0e-3

fix addwater all deposit 20000 1 1000 2015 region slab near 3.0 vz -3.0 -3.0 units box

run 20000000

output file:

Step CPU all_comt TotEng PotEng KinEng Atoms

1430000 5236.2265 300.96256 -421.54838 -504.41674 82.86836 2030
1432000 5250.003 287.46894 -427.26726 -506.13097 78.863703 2032
1434000 5263.8396 302.91931 -423.72964 -506.53196 82.802315 2034
1436000 5277.1322 276.11525 -430.36503 -508.22718 77.86215 2036
1438000 5290.7144 289.89165 -428.71642 -508.90894 80.19252 2038
1440000 5304.0082 297.43659 -425.68669 -508.00274 82.316052 2040
1442000 5317.2449 294.43989 -429.3541 -510.37237 81.018268 2042
1444000 5330.2976 310.32766 -425.2395 -509.54134 84.301843 2044
1446000 5343.4225 493.01668 -398.0041 -515.33698 117.33288 2046
1448000 5357.0297 12144.115 1595.1303 -599.39828 2194.5286 2048
1450000 5371.002 21611.905 3293.1247 -608.664 3901.7887 2050
1452000 5385.2051 34750.058 5662.7718 -608.90745 6271.6792 2052
1454000 5399.5096 46631.01 7809.4875 -611.24441 8420.7319 2054
1456000 5413.6446 63146.407 10795.191 -613.48363 11408.675 2056
1458000 5427.877 83882.26 14539.005 -615.62632 15154.631 2058
1460000 5442.2068 101770.03 17771.023 -618.99532 18390.018 2060