On the large temperature fluctuation of proton water clusters running AIMD

[Mengxu Li (Mengxu)]

Dear all,

       I' m simulating the AIMD of the H+(H2O)3 cluster. I have seen this work, Schran et al., J. Chem. Theory Comput., 16, 88 (2020).  The article explicitly mentioned used parameter settings when simulating AIMD in the article: the cutoff of 500Ry, TZV2P basis set, the time step of 0.25fs, temperature of 300K, Nosé chain thermostat, etc. We have used similar parameter settings and simulated 25ps, but the temperature fluctuation range is large and there is no trend of equilibrium .

        Could you give me some advice? I would appreciate your assistance in my problem.
      PS: the input and output files are attached.

                                                                                                        Yours sincerely,

                                                                                                                 LMX

[钱洁]

Dear Mengxu Li

After reading your inputs, I think there are some parameters you should pay attention to.

1. REGION MASSIVE # too aggressive. global may be better for equilibrium.

2. NOSE LENGTH 5 # 3 or 4 may be suitable

3. REL_CUTOFF  30 # you should test. I suggest 50 or 60.

4. BASIS_SET         DZVP-MOLOPT-SR-GTH # this is good for metals, which may not be suitable for h2o. Please test convergence such as DZVP ,TZVP,TZV2P, etc.

Lastly, I suggest that you can consider the ORCA program for nonperiodic systems.

                                                                                                                                                                            Best wishes,

                                                                                                                                                                            QJ

'Mengxu Li (Mengxu)' via cp2k <cp...@googlegroups.com> 于2022年11月27日周日 14:54写道：

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