[CP2K-user] [CP2K:11312] Re: energy fluctuation in GEO-OPT

Mozhdeh Mohammadpour mozhdehmo... at gmail.com
Thu Feb 21 08:35:17 UTC 2019


Thank you so much for your suggest.
Bests
M.

On Feb 21, 2019 11:49 AM, "Marcella Iannuzzi" <marci... at gmail.com> wrote:

>
> Before getting involved in AIMD simulations, probably you need to go back
> to books to learn about condensed matter electronic structure theory.
> Can your reproduce the electronic properties of this MOF with your DFT
> settings?
> Anyway, to simulate an isolated fragment you need a CELL that is about
> twice as large as the system and you have to choose a proper Poisson
> solver.
> Regards
> Marcella
>
>
> On Thursday, February 21, 2019 at 2:52:47 AM UTC+1, M. Memol wrote:
>>
>> 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" <marc... 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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