dear lammps user

i’m trying to simulate a process of pulling out a single-wall carbon nanotube(cnt) from nature rubber(NR), see the model below ,the box is 30*30*50 and during the simulation, i set velocity for 20 C atoms at the end of CNT and let it go along z-axis, but the whole CNT just don’t move , is there something wrong with my code ?

i’m so sorry if my question was stupid ,i’m new in lammps .

#3D Pull-out Simulation of Carbon nanotube and NR Matrix

units metal

dimension 3

boundary p p s

atom_style atomic

read_data data.heatup

neighbor 2.0 bin

neigh_modify every 1 delay 0 check yes

pair_style hybrid airebo 2.0 tersoff lj/cut 10.0

pair_coeff * * airebo CH.airebo C NULL H

pair_coeff * * tersoff SiC.tersoff NULL C NULL

pair_coeff 1 2 lj/cut 0.0047779 3.65 #CY Wei

pair_coeff 2 3 lj/cut 0.0 0.0

#pair_style airebo 3.0 1 1

#pair_coeff * * CH.airebo C C H

group cnt type 2

group nr type 1 3

region fixedb1 block INF INF INF INF INF 5 units box

group fixedb1 region fixedb1

region fixedbb2 block INF INF INF INF 5 INF units box

group fixedbb2 region fixedbb2

group fixedb2 intersect nr fixedbb2

group fixedb union fixedb1 fixedb2

group nrrest subtract nr fixedb

group cntend id 241:260

group cntrest subtract cnt cntend

group rest subtract all fixedb

#计算

#CNT受力

compute xf cnt reduce sum fx

compute yf cnt reduce sum fy

compute zf cnt reduce sum fz

#温度

#总体温度

compute Tempcntall cnt temp

compute Tempcnt cntrest temp

compute Tempnr nrrest temp

#总体温度分布，不考虑质心运动

compute Tempran all temp/profile 1 1 1 xyz 1 10 10 out bin

compute_modify Tempran dynamic yes

#CNT分环温度

group cnt1 id 1:20

group cnt2 id 21:40

group cnt3 id 41:60

group cnt4 id 61:80

group cnt5 id 81:100

group cnt6 id 101:120

group cnt7 id 121:140

group cnt8 id 141:160

group cnt9 id 161:180

group cnt10 id 181:200

group cnt11 id 201:220

group cnt12 id 221:240

group cnt13 id 241:260

compute Tempnr1 cnt1 temp

compute Tempnr2 cnt2 temp

compute Tempnr3 cnt3 temp

compute Tempnr4 cnt4 temp

compute Tempnr5 cnt5 temp

compute Tempnr6 cnt6 temp

compute Tempnr7 cnt7 temp

compute Tempnr8 cnt8 temp

compute Tempnr9 cnt9 temp

compute Tempnr10 cnt10 temp

compute Tempnr11 cnt11 temp

compute Tempnr12 cnt12 temp

compute Tempnr13 cnt13 temp

#环状温度分布

region cnth cylinder z 15 15 7.5 20.0 INF units box

compute Tempcnth cnt temp/region cnth

region nrh cylinder z 15 15 7.0 20.0 INF units box side out

compute Tempnrh nrrest temp/region nrh

region nr01in cylinder z 15 15 10.0 20.0 INF units box

region nr01 intersect 2 nrh nr01in

compute Tempnr01 nrrest temp/region nr01

region nr01out cylinder z 15 15 10.0 20.0 INF units box side out

region nr02in cylinder z 15 15 12.5 20.0 INF units box

region nr02 intersect 2 nr01out nr02in

compute Tempnr02 nrrest temp/region nr02

region nr02out cylinder z 15 15 12.5 20.0 INF units box side out

region nr03in cylinder z 15 15 15.0 20.0 INF units box

region nr03 intersect 2 nr02out nr03in

compute Tempnr03 nrrest temp/region nr03

region nr03out cylinder z 15 15 15.0 20 INF units box side out

region nr04in cylinder z 15 15 17.5 20 INF units box

region nr04 intersect 2 nr03out nr04in

compute Tempnr04 nrrest temp/region nr04

region nr04out cylinder z 15 15 17.5 20 INF units box side out

region nr05in cylinder z 15 15 20.0 20 INF units box

region nr05 intersect 2 nr04out nr05in

compute Tempnr05 nrrest temp/region nr05

region nr05out cylinder z 15 15 20.0 20 INF units box side out

region nr06in cylinder z 15 15 22.5 20 INF units box

region nr06 intersect 2 nr05out nr06in

compute Tempnr06 nrrest temp/region nr06

region nr06out cylinder z 15 15 22.5 20 INF units box side out

region nr07in cylinder z 15 15 25.0 20 INF units box

region nr07 intersect 2 nr06out nr07in

compute Tempnr07 nrrest temp/region nr07

region nr07out cylinder z 15 15 25.0 20 INF units box side out

region nr08in cylinder z 15 15 27.5 20 INF units box

region nr08 intersect 2 nr07out nr08in

compute Tempnr08 nrrest temp/region nr08

region nr08out cylinder z 15 15 27.5 20 INF units box side out

region nr09in cylinder z 15 15 30.0 20 INF units box

region nr09 intersect 2 nr08out nr09in

compute Tempnr09 nrrest temp/region nr09

timestep 0.0001 #时间步长0.0001 ps，即0.1 fs

#能量最小化

min_style sd

minimize 1.0e-10 1.0e-10 100000 100000

reset_timestep 0

#拉出碳纳米管

velocity fixedb set 0 0 0

fix FIXEDB fixedb setforce 0 0 0

fix NVE all nve

velocity cntend set 0.0 0.0 0.3 sum yes units box #CNT往z+方向移动0.3A/ps,30m/s,108km/h

thermo 5000

thermo_style custom step temp press pe ke evdwl vol density c_xf c_yf c_zf c_Tempcntall c_Tempcnt c_Tempnr

fix Temp_cnt all ave/time 10000 1 10000 c_Tempnr1 c_Tempnr2 c_Tempnr3 c_Tempnr4 c_Tempnr5 c_Tempnr6 c_Tempnr7 c_Tempnr8 c_Tempnr9 c_Tempnr10 c_Tempnr11 c_Tempnr12 c_Tempnr13 file temperature_cnt_zbin.profile

fix Temp_all_cylinder all ave/time 10000 1 10000 c_Tempnr01 c_Tempnr02 c_Tempnr03 c_Tempnr04 c_Tempnr05 c_Tempnr06 c_Tempnr07 c_Tempnr08 c_Tempnr09 file temperature_all_cylinder.profile

fix Temp_all_yzbin all ave/time 10000 1 10000 c_Tempran file temperature_all_yzbin.profile

dump trj all atom 5000 la.lammpstrj

run 1100000 #