[CP2K-user] [CP2K:15662] Re: Dipole Moment. Help wanted.

[Alexander Kazakov]

Dear Mr. Hutter,

thank you for the literature and the recommendations! I will work on it.


Best regards,
Alexander Kazakov

четверг, 1 июля 2021 г. в 11:24:49 UTC+2, jgh: 

> Hi
>
> there are many applications that discuss in more or less details
> the technical aspects. From our group you can start with
>
> General and efficient algorithms for obtaining maximally localized Wannier 
> functions
> G Berghold, CJ Mundy, AH Romero, J Hutter, M Parrinello
> Physical Review B 61 (15), 10040 (2000)
>
> The reference / reference point is specially helpfull if your system has a 
> localized
> source of the dipole, e.g. a polar molecule in solution. It that case you 
> can
> put the reference point close, so that nuclear and electronic 
> contributions are
> as small as possible.
>
> regards
>
> Juerg Hutter
> --------------------------------------------------------------
> Juerg Hutter Phone : ++41 44 635 4491 <+41%2044%20635%2044%2091>
> Institut für Chemie C FAX : ++41 44 635 6838 <+41%2044%20635%2068%2038>
> Universität Zürich E-mail: h... at chem.uzh.ch
> Winterthurerstrasse 190
> CH-8057 Zürich, Switzerland
> ---------------------------------------------------------------
>
> -----c... at googlegroups.com wrote: -----
> To: "cp2k" <c... at googlegroups.com>
> From: "Alexander Kazakov" 
> Sent by: c... at googlegroups.com
> Date: 06/29/2021 12:00PM
> Subject: Re: [CP2K:15662] Re: Dipole Moment. Help wanted.
>
> Dear Mr. Hutter,
>
> thank you for your reply!
>
> @Literature
> I am reading now 2 papers:
> * Nicola A. Spaldin DOI: 10.1016/j.jssc.2012.05.010 -- more about the 
> problem of calculation dipole moment (polarization)
> * Konstantin N. Kudin, Roberto Car, and Raffaele Resta DOI: 
> 10.1063/1.2743018 
>
> Can you, please, suggest more relevant literature?
>
> @Reference point
> Are you talking about this: 
> https://manual.cp2k.org/cp2k-8_1-branch/CP2K_INPUT/FORCE_EVAL/DFT/PRINT/MOMENTS.html#REFERENCE_POINT 
> ?
>
> I see there 4 points which could be a good options, however, all of them 
> has good default values:
>
> * REFERENCE Default value: ZERO
> * REFERENCE_2 Default value: ZERO
> * REFERENCE_POINT Default values: 0.00000000E+000 0.00000000E+000 
> 0.00000000E+000
> * REFERENCE_POINT_2 Default values: 0.00000000E+000 0.00000000E+000 
> 0.00000000E+000
>
> I am not sure that some others values can bring some benefits for the 
> simple cubic system with 64 molecules (sparely distributed).
>
>
> With best regards,
> Alexander Kazakov
>
> понедельник, 28 июня 2021 г. в 10:32:08 UTC+2, jgh: 
> Hi 
>
> dipole moments in periodic systems are only defined modulo 2Pi/L 
> (for simple cubic systems). The value is calculated through a 
> complex Logarithm that can lead to results on different branches 
> with offsets. Have a look at the literature for more complete 
> discussions and more general formulas. 
> The choice of reference point can lead to a reduced number of 
> "jumps" and easier post-processing. 
>
> regards 
>
> Juerg Hutter 
> -------------------------------------------------------------- 
> Juerg Hutter Phone : ++41 44 635 4491 <+41%2044%20635%2044%2091> 
> Institut für Chemie C FAX : ++41 44 635 6838 <+41%2044%20635%2068%2038> 
> Universität Zürich E-mail: h... at chem.uzh.ch 
> Winterthurerstrasse 190 
> CH-8057 Zürich, Switzerland 
> --------------------------------------------------------------- 
>
> -----c... at googlegroups.com wrote: ----- 
> To: "cp2k" <c... at googlegroups.com> 
> From: "Alexander Kazakov" 
> Sent by: c... at googlegroups.com 
> Date: 06/25/2021 03:58PM 
> Subject: [CP2K:15636] Re: Dipole Moment. Help wanted. 
>
> Yeap. Topology is here. 
>
>
> Best regards, 
> Alexander Kazakov 
>
> пятница, 25 июня 2021 г. в 15:55:24 UTC+2, Alexander Kazakov: 
> Dear CP2K community, 
>
> I am simulating 64 molecules of water using DFT in NVT ensemble using PBC. 
> I interested in dipole moment values as a trajectory with MD step. 
>
> Here is what I have so far: 
>
>
> You can see 4 curves: 3 of them are components (x,y,z) and the last one is 
> the length of the vector. All of them are functions of the MD step. 
>
> Let's focus on curves that correspond to x and z components. You can see 
> that there is a kind of "jump" at certain ranges. These "jump" actually 
> resemble a crossing kind of boundary condition. You can see how well it is 
> fit the blue curve on the top to the bottom (the same is applied for the 
> purple curve). 
> Personally, I think it is indeed a kind of boundary condition, however, I 
> have no idea what 30 means. 
>
> Then I found these certain steps where it happens: 
>
> MD STEP 
> 26 
> X= -19.18787840 Y= 5.85693184 Z= 29.55510907 Total= 35.72090144 
> 27 
> X= -19.18076162 Y= 5.52351367 Z= -29.53176935 Total= 35.64458192 
>
> So the z component apparently changed the sign. So I thought that 
> something horrible happened in the system. I plotted position atom change 
> as a function of atom ID: 
> (if the picture has very poor quality, please find enclosed pdf version) 
>
>
> Alright, there is an interesting plot here. We see the different amplitude 
> of change through the atom IDs. So first 2/3 of the curve correspond to 
> hydrogen atoms displacement, whereas the last part corresponds to oxygen 
> atoms. 
>
> So back to questions. Could you tell me, why some components of the dipole 
> moment "jump" changing the sigh? Is it possible to force dipole moment to 
> stay on one side of the "boundary"? There are no doubts that hydrogen atoms 
> should move "actively" than oxygen atoms, but I don't understand what has 
> changed dramatically in the system. Lastly, if you can give me a hint for 
> number 30 in the boundary (see figure), I would be thankful! 
>
> As because I check CP2K 6.1, 7.1, 8.1, and 8.2 and I got the same 
> behaviour with jumps I assume that I did something wrong or misunderstand 
> something. 
> Please find enclosed FORCE_EVAL section of my script. 
>
> Additionally I am sending topology of the system. 
>
> If additionaly information is required, please let me know. 
>
> Best regards, 
> Alexander Kazakov 
>
>
>
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>
>
> [attachment "W64.xyz" removed by Jürg Hutter/at/UZH] 
>
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