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ashioulou

铜虫 (初入文坛)

应助: 5 (幼儿园)
金币: 167.9
帖子: 23
在线: 35.6小时
虫号: 2536624
注册: 2013-07-08
性别: GG
专业: 聚合物共混与复合材料

[求助] NEMD熱傳導性質 NVE能量不守衡問題

小弟目前在做複合材料的熱傳導性質，需要用到NVE系綜做系統平衡
但理論上的NVE為系統總能量需守?a，但目前小弟一直無法做到這點
在系統平衡時溫度會一直上升，能量也會越?碓酱螅恢焙茈y維持在300K
爬了一些文章，發現此種問題可能是跟lammps本身在做NVE積分的時候，
有些誤差累積所造成能量疊加上升。
但小弟的case上升的非常誇?垼瑢n文件貼出，希望有先進可以指點一二
=================================================
units    real
dimension  3
boundary p p p
atom_style full

kspace_style pppm 1e-6
pair_style lj/class2/coul/long 10.0 10.0
pair_modify  mix sixthpower
bond_style class2
angle_style class2
dihedral_style class2
improper_style class2
neighbor 3.0 nsq
read_restart composite.restart.1200000

region 1 block  INF INF INF INF 0       2.4740  units box
region 2 block  INF INF INF INF 2.4740 4.9480  units box
region 3 block  INF INF INF INF 4.9480 7.4220  units box
region 4 block  INF INF INF INF 7.4220 9.8960  units box
region 5 block  INF INF INF INF 9.8960 12.370  units box
region 6 block  INF INF INF INF 12.370 14.844  units box
region 7 block  INF INF INF INF 14.844 17.318  units box
region 8 block  INF INF INF INF 17.318 19.792  units box
region 9 block  INF INF INF INF 19.792 22.266  units box
region 10 block INF INF INF INF 22.266 24.740  units box
region 11 block INF INF INF INF 24.740 27.214  units box
region 12 block INF INF INF INF 27.214 29.688  units box
region 13 block INF INF INF INF 29.688 32.162  units box
region 14 block INF INF INF INF 32.162 34.636  units box
region 15 block INF INF INF INF 34.636 37.110  units box
region 16 block INF INF INF INF 37.110 39.584  units box
region 17 block INF INF INF INF 39.584 42.058  units box
region 18 block INF INF INF INF 42.058 44.532  units box
region 19 block INF INF INF INF 44.532 47.006  units box
region 20 block INF INF INF INF 47.006 49.480  units box
region 21 block INF INF INF INF 49.480 51.954  units box
region 22 block INF INF INF INF 51.954 54.428  units box
region 23 block INF INF INF INF 54.428 56.902  units box
region 24 block INF INF INF INF 56.902 59.376  units box
region 25 block INF INF INF INF 59.376 64.324  units box
region 26 block INF INF INF INF 121.226 123.7  units box
region cold union 2 1 26 units box

group source region 25
group sink region cold
group 1 region 2
group 2 region 3
group 3 region 4
group 4 region 5
group 5 region 6
group 6 region 7
group 7 region 8
group 8 region 9
group 9 region 10
group 10 region 11
group 11 region 12
group 12 region 13
group 13 region 14
group 14 region 15
group 15 region 16
group 16 region 17
group 17 region 18
group 18 region 19
group 19 region 20
group 20 region 21
group 21 region 22
group 22 region 23
group 23 region 24

fix 1 all nve

compute temps sink temp
compute temp1 1 temp
compute temp2 2 temp
compute temp3 3 temp
compute temp4 4 temp
compute temp5 5 temp
compute temp6 6 temp
compute temp7 7 temp
compute temp8 8 temp
compute temp9 9 temp
compute temp10 10 temp
compute temp11 11 temp
compute temp12 12 temp
compute temp13 13 temp
compute temp14 14 temp
compute temp15 15 temp
compute temp16 16 temp
compute temp17 17 temp
compute temp18 18 temp
compute temp19 19 temp
compute temp20 20 temp
compute temp21 21 temp
compute temp22 22 temp
compute temp23 23 temp
compute temph  source temp

fix 2 source heat 4 0.01
fix 3 sink heat 4 -0.01

thermo    1
variable density equal mass(all)*10/(6.0221417930*vol)
thermo_style custom step temp etotal  c_temph
dump       out1 all custom  200 dump.lammpstrj id type x y z
timestep 0.25
restart 100000 epon.restart
run 1200000
==================================================
我所選用的勢能函數為PCFF 先做NVT系統平衡到300K 再做NVE
有試著修改過ksapce pppm---> ksapce ewald 但結果還是一樣
也有更改過pair_style lj/class/coul/cut 10.0 8.0 結果一樣
最後做出?淼南到y溫度會上升到700多K ，如果在平衡更久溫度會在更高
不知道各位還有沒有什麼其他的想法，可以改進問題
能讓系統維持在300K左右(熱傳導與系統本身的溫度有關係)
我怕雖然做得出?淼膖emp gradient，但結果不是在300K時材料的熱傳導值

希望大家提出建議交流交流一下!!  謝謝!!!!!!!!

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