[Pw_forum] relaxing a vacancy in diamond

[Nandan Tandon]

Thanks Giuseppe.

Nandan.

On Wed, Feb 7, 2018 at 5:49 AM, Giuseppe Mattioli <
giuseppe.mattioli at ism.cnr.it> wrote:

>
> > Or just shifting the atoms slightly before starting the relaxation?
>
> Yes! If the code finds a starting symmetry, it does not break it.
>
> HTH
> Giuseppe
>
>
> Quoting Nandan Tandon <nandan.tandon at gmail.com>:
>
> > Hi,
> >
> > I am trying to relax a vacancy in a cubic 512 atom unit cell of diamond.
> It
> > has
> > been seen that the T_d symmetry around the vacancy is lowered to D_{2d}.
> > But my system does not show this because all the atoms (first 4
> neighbors)
> > around the vacancy are at identical distances from the vacancy and each
> > other.
> >
> > Initially, using a FCC supercell also gave the same relaxed structure.
> This
> > prompted me to start with a cubic structure.
> >
> >
> > My question is, is there a trick to do such vacancy calculations?
> >
> > Like starting by substituting a carbon atom with another atom to distort
> > the lattice
> > before creating a vacancy at the site?
> >
> > Or just shifting the atoms slightly before starting the relaxation?
> >
> > I have done few tests to ensure that the Ecut is high (80Ryd), its a
> Gamma
> > point calculation, LDA potentials and an optimized lattice constant.
> >
> > Thanks and regards,
> >
> > Nandan.
> > --
> > ************************************************************
> ***********************************
> > Nandan Tandon
> > Michigan State University
> > East Lansing
> > Michigan 48824-1226
> > ************************************************************
> *************************************
>
>
>
> GIUSEPPE MATTIOLI
> CNR - ISTITUTO DI STRUTTURA DELLA MATERIA
> Via Salaria Km 29,300 - C.P. 10
> I-00015 - Monterotondo Scalo (RM)
> Mob (*preferred*) +39 373 7305625
> Tel + 39 06 90672342 - Fax +39 06 90672316
> E-mail: <giuseppe.mattioli at ism.cnr.it>
>
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-- 
***********************************************************************************************
Nandan Tandon
Michigan State University
East Lansing
Michigan 48824-1226
*************************************************************************************************
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