[CP2K-user] [CP2K:11308] Re: energy fluctuation in GEO-OPT

Mozhdeh Mohammadpour mozhdehmo... at gmail.com
Thu Feb 21 01:52:43 UTC 2019


Thank you so much for your response. Actually I am an Abinitio user and I
am very new in AIMD. And the part MD is a kind of black box for me. But
before doing AIMD, and along with studying precious book of prof. Hutter, i
decided to get familliar to the program package with the aid of the
excerices. Yes this an isolated part of a crystal. A first building block
of a MOF. Before your answer, I did some modification in the input. For
example i turned on the periodic option and as a result, the menrioned
fluctuation disappeared and scf coverged. But what if I do not want to use
periodic system and just optimize this isolated part?

On Feb 20, 2019 6:19 PM, "Marcella Iannuzzi" <marci... at gmail.com> wrote:

> Either the structure or the DFT setting must have serious problems, since
> the SCF is never converging.
> For example in SUBSYS you use "periodic none" with a box of 15 Å, but your
> system seems to be larger than that.
> On the other hand, POISSON is still using PBC.  What do you want to model,
> an isolated subsystem of a crystal?
> With such a wrong electronic structure you cannot expect any meaningful
> evaluation of the forces.
> Before starting the GEO_OPT you need to be able to get a reasonable
> electronic structure of the initial state.
>
> Regards
> Marcella
>
> On Wednesday, February 20, 2019 at 6:16:39 AM UTC+1, M. Memol wrote:
>>
>> I am a very recent user of cp2k and I am really sorry if my question is a
>> naive one. I am getting familiar with calculation by cp2k. I am doing an
>> geometry optimization run on a MOF building block. But comparing to the
>> examples, the energy fluctuates. input and output are given below. any
>> comment?
>> thanks in advance
>>
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