[CP2K-user] different version of cp2k different energy

Xin Wei goweix... at gmail.com
Thu Jul 30 17:50:07 UTC 2020

Thank you! it's really helpful. 

On Wednesday, July 29, 2020 at 2:55:46 AM UTC-4, Fabian Ducry wrote:
> Hi Xin,
> It depends on the system you are simulating, e.g. molecules and 2D 
> materials often profit from a vdw correction. For bulk materials however, 
> the correction may lead to too short bond lengths. Make sure to check for 
> your input. Also compare different vdw corrections.
> Fabian
> On Tuesday, 28 July 2020 21:31:24 UTC+2, Xin Wei wrote:
>> Hi Fabian, 
>> Thank you very much! I didn't notice that one input file doesn't have VDW 
>> correction before. I tried the same input file for different versions of 
>> CP2K and the results are close. It's better to include the VDW correction 
>> in the calculations, right? 
>> Xin
>> On Tuesday, July 28, 2020 at 3:03:01 AM UTC-4, Fabian Ducry wrote:
>>> Hi Xin,
>>> Have you tried to run both input files with the same version of cp2k? 
>>> That would be the easiest test whether there is a problem or not. 
>>> The two input files are quite different in fact: You are using two 
>>> exchange-correlation functionals: one has a VDW correction while the other 
>>> does not. So you cannot expect to get the same energy, not even similar 
>>> values.
>>> Best,
>>> Fabian
>>> On Tuesday, 28 July 2020 01:22:29 UTC+2, Xin Wei wrote:
>>>> Hi Everyone, 
>>>> I did the geometry optimization using similar input files for the same 
>>>> structure but different versions of cp2k --cp2k6.1 and cp2k7.1. (The input 
>>>> files are attached) The final energy calculated is different and the 
>>>> difference is -339.071 KJ/mol. I am wondering what caused this difference. 
>>>> Are different versions of cp2k using different reference energy? If so, may 
>>>> I know what is the reference energy? 
>>>> Thanks a lot!
>>>> Xin
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