[QE-users] ESM calculation with tot_charge in QE

[Paolo Giannozzi]

The ESM-RISM extension of QE, written by Satomichi Nisihara, is available
here:
   https://github.com/nisihara1/q-e
It is currently aligned to QE v.6.1

Paolo

On Thu, Mar 15, 2018 at 12:05 PM, Giuseppe Mattioli <
giuseppe.mattioli at ism.cnr.it> wrote:

>
> Dear Minoru
> I've read the PRB paper you suggested and I would be very interested in
> testing such a new 3D-RISM extension of the ESM method of yours. The paper
> mention a QE implementation, but I've not seen any documentation in QE
> 6.2.1 yet. Shall I find it either in the unstable version or in a next
> stable release?
> Thank you in advance
> Giuseppe
>
>
> Quoting 大谷?g <minoru.otani at aist.go.jp>:
>
> Dear Hong,
>>
>> In the boundary condition bc1, i.e. the open boundary condition, we need
>> to prepare a neutral system. Because there are divergent terms in the total
>> energy and the electrostatic potential. If your system is neutral, i.e.
>> tot_charge=0, you can get an appropriate result with ESM, but your system
>> is charged, i.e. tot_charge!=0, you can not get a physically meaningful
>> result.
>>
>> In other boundary conditions such as bc2 and bc3, the ESM automatically
>> introduce compensation charge. Thus the whole system is neutral. In other
>> words, there are no divergent terms in the total energy and the
>> electrostatic potential for bc2 and bc3.
>>
>> As you can understand from above description, the problem is the
>> divergent term. If you can ensure that the additional charge induced in the
>> system with bc1 will completely be screened by another medium, you can use
>> the bc1 boundary condition. In this case, the total energy and the
>> electrostatic potential are physically meaningful values. In other words,
>> the divergent term from another medium eliminates that from the system.
>>
>> If you want to dig into the details of this, you can read the following
>> paper: Phys Rev. B 96, 115429 (2017).
>>
>> In short, you can not use bc1 with a charged system.
>>
>> Best regard,
>> Minoru
>>
>> ------------------------------------------------------------
>> --------------------------------------------
>> National Institute of Advanced Industrial Science and Technology,
>> Research Centre for Computational Design of Advanced Functional Materials
>> E-mail: minoru.otani at aist.go.jp
>> ------------------------------------------------------------
>> --------------------------------------------
>>
>>
>> ________________________________________
>> From: users <users-bounces at lists.quantum-espresso.org> on behalf of
>> Honghui Wu <hhwuaa at connect.ust.hk>
>> Sent: Saturday, March 10, 2018 2:38:38 AM
>> To: users at lists.quantum-espresso.org
>> Subject: [QE-users] ESM calculation with tot_charge in QE
>>
>> Dear all,
>>
>> Can we use the charged system (tot_charge= a finite value) with the
>> vacuum-slab-vacuum boundary condition (esm_bc = 'bc1') in Quantum
>> ESPRESSO?
>>
>> In the OpenMX website, I find the ESM developer writes 'ESM.switch =
>> on1: Both ESM (I) and (II) are semi-infinite vacuum media. In this case,
>> note that the total charge of a calculation system should be neutral.
>> The keyword 'scf.system.charge' should be set to be zero.'.
>> However, I did not find the similar description of the esm_bc= 'bc1' :
>> Vacuum-slab-vacuum (open boundary conditions).  Does it mean we can use
>> the charged system (tot_charge= a finite value) with the
>> vacuum-slab-vacuum boundary condition in Quantum ESPRESSO?
>>
>> Thank you!
>>
>> Best regards,
>> Hong
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>
>
>
> GIUSEPPE MATTIOLI
> CNR - ISTITUTO DI STRUTTURA DELLA MATERIA
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> E-mail: <giuseppe.mattioli at ism.cnr.it>
>
>
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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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