[Wien] basic-question-about-mini-PORT

[Laurence Marks]

Inlined


-----------------------------------
Professor Laurence Marks
"Research is to see what everybody else has seen, and to think what nobody
else has thought", Albert Szent-Gyorgi
www.numis.northwestern.edu ; Corrosion in 4D: MURI4D.numis.northwestern.edu
Partner of the CFW 100% program for gender equity, www.cfw.org/100-percent
Co-Editor, Acta Cryst A

On Mon, Feb 15, 2016 at 11:08 PM, ‪Amir lot‬ ‪‬ <lot.amir at yahoo.com> wrote:

> Dear WIEN2k users,
> As I can guess mini or PORT program works as:
> The program gets Energy ( and forces) of compound and positions of atoms
> which have forces.
> PORT program using these data provides next new positions related to atoms
> which have forces.
> using new generated struct file with new positions, the PORT program does
> a scf.
> Now, The program gets new energy of compound with new positions of atoms
> which have forces and produces next new positions.
> The PORT repeats the above steps till forces drops  below for example 1 .
>
>
> First question
> Are the above steps correct?
>

Yes

>
> second question
> How does PORT produces equivalent positions related to new positions When
> the program want to generate the new struct file with new positions?
>

It uses the symmetry relations between the positions which are at the end
of case.struct

>
> Third question
> When the positions of atom are as X=Y=Z, Does PORT program get only energy
> and for example X position or energy and (X,Y,Z) positions as input data?
> Because when (X=Y=Z) and PORT program get (X,Y,Z) as a input data may
> produces new positions as (Xn#Yn#Zn) which make error because (X=Y=Z).
>

Port obeys the symmetry relationships. If due to these X=Y=Z the atomic
positions always obey this constraint. If no symmetry forces this the
positions may change so this is no longer an equality. Symmetry rules.

N.B., MSR1a is similar, but does not use the forces in the same way and
ignores the energy.

>
>
> With best,
> Amir
>
>
>
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