既然是在nve系综下跑，温度出现变化也是正常的吧，只要能量保持在一个波动平衡下就没问题吧

Usually it's because the equilibration stage is not long enough (There can be many other reasons, though).
What is your time step and how many steps for the NVT and NPT runs?

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2楼: Originally posted by cl1994861 at 2017-06-02 10:46:35
既然是在nve系综下跑，温度出现变化也是正常的吧，只要能量保持在一个波动平衡下就没问题吧

No, the temperature in the production NVE run is supposed to have a stable average value. An increasing temperature is a sign of problem
，

应该是系统没有完全平衡好吧，只能这么理解了

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5楼: Originally posted by jmforever123 at 2017-06-03 11:49:45
the time step is 0.8fs, npt,2000000, nvt1000000
...

The time step might be too large. try smaller values, such as 0.2 fs or even 0.1 fs.