[Pw_forum] PlotPhon Questions

[W2AGZ]

To the Forum, I'm sure my inquiry will wind up on the doorstep of Eyvaz, so
I'll address this directly to him shortly.

 

But firstly, let me echo Stephano's New Year's Greeting...it could not have
been put more eloquently...unless it had been in Italian!  In fact, I think
we can all celebrate again in another two weeks on the occassion of the "old
Russian New Year's." 

 

I, too, am a fan of Jean Piaget, and one my favorite quotes (in English) is,
"Scientific knowledge is in perpetual evolution; it finds itself changed
from one day to the next."  The Democritos movement is at the forefront of
such evolution worldwide, and, in fact, imho, thus deserves the Peace Prize
much more than the recipient two years ago.

 

OK...to business.  Eyvaz, 

1)      Thanks very much for creating PlotPhon.  It's a great contribution
to the "QE toolbox."

2)      Could you supply us the input files for pw.x and ph.x that created
the output for q2r.x to process into the *.fc files for the "three
examples?"

3)      In particular, and especially, for AL_FCC and Al444.fc.  I typically
use the Al parameters of Example 07 and the *.fc files don't match, even
when I use your value of the lattice constant.  (Ex07 uses a lattice
constant of 7.50 au, and PlotPhon uses 7.653 (??), while I usually use 4.050
(Ang))

4)      Now for a question likely very naive...

a.       Al444.fc contains something like 584 permutations on "interatomic
force constants," indexed according the 4x4x4 MP input.  It seems to me that
there are (perhaps) two different nearest-neighbor Al-Al distances in the
fcc unit cell, so...

b.      Is there a simple way to relate the *.fc output into pairwise
"interatomic force constants?"

 

OK...Otro vez, Feliz Anyo Nuevo a los Todos y mucho mas in el Futuro.

 

-          Paul Grant

-          Senior Life Fellow, American Physical Society

-          w2agz at w2agz.com

-          www.w2agz.com

 

 

 

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