24小时热门版块排行榜

返回列表

小金鱼吐泡泡

银虫 (小有名气)

应助: 0 (幼儿园)
金币: 432.1
红花: 1
帖子: 66
在线: 80.1小时
虫号: 2498884
注册: 2013-06-06
专业: 钢铁冶金

[求助] lammps计算石墨烯的热导率的问题

最近用fix heat命令来计算0.369*10nm石墨烯纳米带的热导率，但是冷热区域的温度一直乱跳，温差也不稳定。求各位大神帮我看一下，这是什么原因造成的。
in文件如下：
#settings

boundary  s s s
units  metal
dimension  3
atom_style  atomic
neighbor 2.0 nsq
read_data data.graphene
pair_style  airebo 3.0 1 0
pair_coeff * * CH.airebo  C
  timestep  0.0005

#heat layers

region  box  block 0.0 100.820 0.0  3.69 0.0  0.5 units box
region begin    block 0.00       4.26    INF INF  INF  INF units box
region hot       block 4.26       15.62    INF INF  INF  INF units box
region a       block 38.34    42.6    INF INF  INF  INF units box
region a1       block 58.22    62.48    INF INF  INF  INF units box
region cold    block 85.2    96.56    INF INF  INF  INF units box
region end       block 96.56    100.82 INF INF  INF  INF units box
region boundary union 2  begin end  units box
group begin region  begin
group hot    region  hot
group a    region  a
group a1    region  a1
group cold    region  cold
group end    region  end
group boundary  region boundary
group 1  subtract all boundary

velocity  1  create 300 7986875  rot yes dist gaussian units box
velocity boundary  set 0.0  0.0  0.0  units box

compute Thot hot temp
compute Tcold  cold  temp
compute Ta    a    temp
compute Ta1 a1 temp
#1st equilibration run

fix 1  boundary setforce 0.0 0.0 0.0
fix 2 1 nvt temp 300 300 0.025

thermo 20000
run 200000
velocity 1 scale 300
unfix 2
#2nd equilibration run


  fix 2  1 nve
  fix hot all  heat  1  0.05 region hot
  fix cold  all  heat  1  -0.05  region  cold
  thermo_style custom step temp c_Thot c_Tcold c_Ta c_Ta1
  thermo 20000
  run 200000
# thermal conductivity calculation
compute ke 1 ke/atom
variable  temp  atom  c_ke*1.6e+4/(1.5*1.38)
fix  3  1 ave/spatial 1 10000  10000  x (0,0,0) 2  v_temp  file  temp.profile

units  box
variable  tdiff equal c_Ta-c_Ta1
fix  ave  1  ave/time 1  10000 10000 v_tdiff file temp.dat


thermo_style custom step temp c_Thot c_Tcold  c_Ta c_Ta1  v_tdiff f_ave


dump 1  all  xyz  100  6.xyz


run  500000
温度变化如下：
Step Temp Thot Tcold Ta Ta1 tdiff ave
  400000 269.23691    287.8761 275.76215    313.213 345.55155 -32.338554          0
  420000 269.81787 309.14147 290.74161 306.74933 278.18371 28.565624  -0.17454591
  440000 272.44091 291.93314 252.25398 325.61845 285.88274 39.735712 5.3615387
  460000 263.11957 282.83603 294.60785 328.46543 339.10522 -10.639792 0.72550078
  480000 267.50892 258.29901 295.67927 310.05181 282.70234 27.349472 -1.0118141
  500000    269.4477 313.28237 266.60693 309.37086 334.99781 -25.626954 -10.320397
  520000 262.99489 271.05986 291.59293 263.63293 278.23083 -14.597901 -11.319708
  540000 260.10253 275.77656 249.27972 307.51494    270.9557 36.559236 5.4956093
  560000 259.27978 273.88015 229.38609 315.03635 285.08593 29.950418 -14.092973
  580000 267.77467    283.3978 286.68541 348.22233    290.4835 57.738832 -6.4775073
  600000 274.51824 305.18136 244.07701    319.8226 347.35808 -27.535478 9.6719984
  620000 257.74313 294.67026 270.37505 204.79405 332.79866 -128.00461 -1.740932
  640000 274.23782 257.42194 279.52465 297.56328 337.38293 -39.819641 -5.6389268
  660000 260.50736 271.26666 278.35298 297.69454 272.71023 24.984313 8.7531248
  680000 263.98599 277.09742 277.49638 317.79667    311.4145 6.3821692 8.6367117
  700000    264.7486    258.675 250.74464 256.10613 272.31152 -16.205395    1.58886
  720000 262.98104 264.01152 292.27107 250.05507 266.07286 -16.017796 12.698902
  740000 271.19711 270.11872 265.75762 268.41015 317.86751 -49.457365 18.860406
  760000 269.60242 261.94431 271.51483    290.1973 336.06057 -45.863267 -10.896141
  780000 259.37708 274.50601 264.52134 314.59913 260.00687 54.592267 -5.5865446
  800000    263.3127 272.23833 265.13967 288.14276    250.2414 37.901358 14.130534
  820000 259.99085 272.12302 303.32491 280.12599 295.63615 -15.510163 9.1282407
  840000 258.50555 248.03292 243.83503 316.68307 371.23487 -54.551797 13.057586
  860000 264.49959 297.17635 289.06594 323.03424 323.87308  -0.83883968 6.1678109
  880000 272.43133 312.02931 305.26441 279.30288    284.1514 -4.8485185 9.6518555
  900000 268.45492 317.78074 272.89921 309.72521 283.49758 26.227631 -17.96542
  920000 275.40794 297.66056 282.53015 375.59481 241.89243 133.70238 -8.9195466
  940000 264.03844 275.22935 255.23617 334.46814 251.03495 83.433183    6.604159
  960000 270.86631 295.12417    286.933 316.39165 325.42678 -9.035132 18.053482
  980000 267.30146 269.03751 271.88812 279.22782 294.31897 -15.091146 -1.7402468
1000000 265.70605 263.06816 265.72979 296.66431 272.15849 24.505825 -1.8674673
1020000    257.1274 291.33817 224.22826 318.79186 287.17339    31.61847 -12.680947
1040000 271.39067 336.14538 235.04786 299.97461 294.62197 5.3526333    17.69643
1060000 266.63154 275.16562 291.28959 313.47423 276.48449 36.989741 -3.1525017
1080000 255.17158    285.5913 265.00618 286.24291 297.36401 -11.121097 7.3465889
1100000 257.51466 247.58114 276.95258 332.18926    245.0088 87.180457 15.041541
1120000 263.72975    269.3746 263.84122 368.41537 361.65871 6.7566642 -13.833455
1140000 274.21982 301.24577    258.0196 429.09229 353.24198 75.850306 8.8486513
1160000    265.3743 323.12818 304.82505 273.15695 222.13356 51.023385 -5.7061837
1180000 268.50241 286.55139 257.53396 337.00051 304.68809 32.312416 -7.6532385
1200000 261.89366 292.93298 249.67683    309.473    340.2156 -30.742604 10.270989
1220000 255.03955    246.1148    286.7719 337.52998 291.19961 46.330363 2.3437229
1240000    268.089 270.25406 244.02854 360.95777 325.57175 35.386021 2.6982092
1260000    264.2253 274.89726 305.76079 417.34362    274.5644 142.77923 -6.330006
1280000 261.64892 279.88026 279.64804 233.71333 299.24483 -65.531504 6.9693311

回复此楼