the temperature increases to about 10000K suddenly

Dear all,
I try to do a simulation with reax/c and the input file is shown as follows:

# REAX potential for CuO-C3H6-O2 system
# …

units real

atom_style charge

read_data data.Cu

pair_style reax/c lmp_control
pair_coeff * * ffield.reax H C O Cu

neighbor 2 bin
neigh_modify every 10 delay 0 check no

timestep 0.25
fix 1 all qeq/reax 1 0.0 10.0 1e-6 param.qeq

thermo_style custom step elapsed elaplong dt time temp epair ke pe etotal press
thermo 1
group freeze id 3030:5330:4 3031:5331:4 234:2522:16 238:2526:16 226:2514:16 230:2518:16 235:2523:16 239:2527:16 227:2515:16 231:2519:16
fix 2 freeze setforce 0.0 0.0 0.0
fix 3 all nvt temp 300.0 300.0 25.0
fix 4 all temp/berendsen 300.0 300.0 25.0
fix 5 all reax/c/bonds 100 bond1.reaxc
dump 1 all custom 10 dump1.custom id element x y z
dump_modify 1 sort id element H1 C2 O3 Cu4 format float %15.8f
run 40000
write_restart restart.Cu1
unfix 3
unfix 4
unfix 5
fix 6 all nvt temp 300.0 550.0 25.0
fix 7 all temp/berendsen 300.0 550.0 25.0
fix 8 all reax/c/bonds 100 bond2.reaxc
undump 1
dump 2 all custom 10 dump2.custom id element x y z
dump_modify 2 sort id element H1 C2 O3 Cu4 format float %15.8f
run 100000
write_restart restart.Cu2
unfix 6
unfix 7
unfix 8
fix 9 all nvt temp 550.0 550.0 25.0
fix 10 all temp/berendsen 550.0 550.0 25.0
fix 11 all reax/c/bonds 100 bond3.reaxc
undump 2
dump 3 all custom 10 dump3.custom id element x y z
dump_modify 3 sort id element H1 C2 O3 Cu4 format float %15.8f
restart 100000 restart.*.Cu
run 4000000
write_restart restart.Cu3
But during the simulation, I have found that the temperature increases to about 10000K suddenly and a part of log.lammps is shown as follows:
Step Elapsed Elaplong Dt Time Temp E_pair KinEng PotEng TotEng Press
594736 454736 454736 0.25 148684 549.44039 -485363.13 8732.6292 -485363.13 -476630.5 -1047.8445
594737 454737 454737 0.25 148684.25 552.36913 -485422.43 8779.1777 -485422.43 -476643.26 -1098.8566
594738 454738 454738 0.25 148684.5 557.12328 -485518.36 8854.7387 -485518.36 -476663.62 -1169.9256
594739 454739 454739 0.25 148684.75 565.26206 -485683.2 8984.0938 -485683.2 -476699.11 -1282.6319
594740 454740 454740 0.25 148685 581.98438 -486021.4 9249.873 -486021.4 -476771.53 -1537.248
594741 454741 454741 0.25 148685.25 644.69829 -487181.25 10246.628 -487181.25 -476934.62 -2683.3005
594742 454742 454742 0.25 148685.5 3717.9898 -484825.01 59092.537 -484825.01 -425732.47 -21447.667
594743 454743 454743 0.25 148685.75 10282.298 -482365.38 163423.55 -482365.38 -318941.84 11078.274
594744 454744 454744 0.25 148686 10130.669 -481452.89 161013.6 -481452.89 -320439.28 10864.559
594745 454745 454745 0.25 148686.25 10117.441 -483398.47 160803.37 -483398.47 -322595.1 10768.316
594746 454746 454746 0.25 148686.5 9958.3746 -483870.39 158275.21 -483870.39 -325595.18 10546.962
594747 454747 454747 0.25 148686.75 9806.3326 -484283.02 155858.7 -484283.02 -328424.31 10341.498
594748 454748 454748 0.25 148687 9649.7841 -484300.46 153370.57 -484300.46 -330929.89 10102.839
594749 454749 454749 0.25 148687.25 9481.2192 -484109.24 150691.46 -484109.24 -333417.79 9875.3735
594750 454750 454750 0.25 148687.5 9312.251 -483920.81 148005.93 -483920.81 -335914.88 9567.5294
594751 454751 454751 0.25 148687.75 9146.8593 -484083.72 145377.25 -484083.72 -338706.47 9457.764
594752 454752 454752 0.25 148688 8983.0301 -484182.63 142773.4 -484182.63 -341409.23 9249.7572
594753 454753 454753 0.25 148688.25 8817.5708 -484253.98 140143.64 -484253.98 -344110.34 9046.0834
594754 454754 454754 0.25 148688.5 8647.3548 -484216.28 137438.28 -484216.28 -346778 8841.2399
594755 454755 454755 0.25 148688.75 8473.9125 -484126.99 134681.65 -484126.99 -349445.34 8622.5078
594756 454756 454756 0.25 148689 8303.4239 -484002.81 131971.96 -484002.81 -352030.86 8410.8731
594757 454757 454757 0.25 148689.25 8144.0468 -484025.78 129438.87 -484025.78 -354586.92 8222.4378
594758 454758 454758 0.25 148689.5 7991.9776 -484122.27 127021.93 -484122.27 -357100.34 8018.737
Moreover, the simulation exited abnormally as follows:
601520 461520 461520 0.25 150380 2935.5921 -489296.08 46657.36 -489296.08 -442638.72 2085.3789
601521 461521 461521 0.25 150380.25 2859.3263 -489071.52 45445.215 -489071.52 -443626.3 1990.1863
601522 461522 461522 0.25 150380.5 2788.1154 -488817.55 44313.412 -488817.55 -444504.14 1898.2934
601523 461523 461523 0.25 150380.75 2739.2848 -489053.09 43537.314 -489053.09 -445515.78 1850.6748
601524 461524 461524 0.25 150381 2697.4712 -489308.41 42872.742 -489308.41 -446435.67 1812.0868
601525 461525 461525 0.25 150381.25 2648.3772 -489398.39 42092.458 -489398.39 -447305.93 1740.696
601526 461526 461526 0.25 150381.5 11028.619 -486734.31 175285.33 -486734.31 -311448.99 -10587.208
601527 461527 461527 0.25 150381.75 27360.237 -488036.22 434854.83 -488036.22 -53181.381 31632.182
601528 461528 461528 0.25 150382 26341.654 -489091.52 418665.79 -489091.52 -70425.727 30572.666
601529 461529 461529 0.25 150382.25 25383.141 -489397.96 403431.5 -489397.96 -85966.456 29392.83
601530 461530 461530 0.25 150382.5 24443.949 -489279.67 388504.28 -489279.67 -100775.39 28232.546
601531 461531 461531 0.25 150382.75 5.5 -5343198.4 87.415236 -5343198.4 -5343111 -29232481
ERROR: Computed temperature for fix temp/berendsen cannot be 0.0 (…/fix_temp_berendsen.cpp:150)
Last command: run 4000000
Could you tell me the reasons that result in it and how can I correct it? Thanks.
Best regards,
Jie Wang

It may be because you are integrating with fix nvt while having fix temp/berendsen enable at the same time.

From the docs on fix temp/berendsen: Likewise, this fix should not normally be used on atoms that also have their temperature controlled by another fix - e.g. by fix nvt or fix langevin commands.

You can try using fix nve all nve instead?

Anders