[QE-users] Charge distribution between two separate objects

[Dan Gil]

I ran three simulations: (1) Water and quartz, (2) quartz only, and (3)
water only.

With pp.x I obtained the electron density along a coordinate for each
simulation. Then I did:
deltaRho = Rho(Water&Quartz) - Rho(WaterOnly) - Rho(QuartzOnly)

Which yielded how the electron density is perturbed on each object when
they are in proximity. I integrated the region around water to obtain the
"charge." This region was small compared to the distance of separation
(~0.5 nm region vs. 3 nm separation). Outside this region, deltaRho was
equal to 0.

Dan


On Tue, Oct 16, 2018 at 3:42 AM Paolo Giannozzi <p.giannozzi at gmail.com>
wrote:

> How did you compute the "charge on water"?
>
> Paolo
>
> On Mon, Oct 15, 2018 at 5:57 PM Dan Gil <dan.gil9973 at gmail.com> wrote:
>
>> Dear QE Users,
>>
>> I am trying looking at how the electron density redistributes itself when
>> two objects are in close proximity. The two objects in questions is a water
>> molecule and a quartz (001) crystal.
>>
>> At far distances (> 1 nm) between the water and the quartz, I expect
>> (very close to) zero charge on either water or quartz. However, I am
>> finding the contrary. At 3 nm between (defined as the distance between two
>> closest atoms) the charge on water is ~0.01 e.
>>
>> I am wondering if this result is expected due to the computational
>> limitations... Or if I can mitigate this problem with a computationally
>> efficient way.
>>
>> Best Regards,
>>
>> Dan Gil
>> PhD Candidate
>> Dept. Chemical and Biomolecular Engineering
>> Case Western Reserve University
>>
>>
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>
>
>
> --
> Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
> Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
> Phone +39-0432-558216, fax +39-0432-558222
>
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