The ABINIT Users Mailing List ( CLOSED )

[paul fons <paul-fons@aist.go.jp>]

Let me start out by thanking you for your hard work on atompaw.  It is greatly appreciated by myself and I am

sure many others on this list.  I am also happy to see the rapid development of atompaw.  Your comments in your last

two emails have been most helpful.  I shall look forward to hearing more when you have time (I know how busy schedules

can get!).  I have enough to get started now and am closing in on the "needs to be tested by the user..." part of your

recommendations! 

Thanks again,

Paul

On Apr 17, 2007, at 9:49 PM, Natalie Holzwarth wrote:

Dear Paul,

     Some comments are listed below:

On Mon, 16 Apr 2007, Paul Fons wrote:

   I was attempting to go through the examples on the Lake

Forest page (http://www.wfu.edu/%7Enatalie/papers/pwpaw/periodictable/

periodictable.html).  On the Lake Forest page, the downloadable

potentials seem to be of two flavours as reinforced by the somewhat

cryptic label "Modified Elements" and "Unmodified Elements".  I

didn't find a reference anywhere as to what these terms meant (pardon

me if it was just my oversight).     We are trying to update the webpage

which was created in 2005 by a summer student, using the more recent

version of the programs.   The "modified elements" are the ones we have

worked on so far.      Of course, even if we have worked on an element, it

still needs to be tested by the user....

I was curious to follow up on the mail by Natalie Holzwarth. First,

the general guidelines in her email appear to be useful and provided

some new information to me that I hadn't considered (e.g. the

inclusion of positive energy states).  I wanted to take this

opportunity to ask a couple of (what I hope aren't too) simple

questions.

1. On the Lake Forest periodic table of PAW potentials, most of the

potentials (the "unmodified" ones?) seem to use PS of the Trouiller-

Martin norm conserving form using the Blochl scheme.  This would

appear to have the advantage that there are fewer parameters to tweak

(I am assume this is also its disadvantage!).  The new entries seem

to use T-M PS, but with the Vanderbilt scheme.

I was hoping that Natalie (or another person from her research group)

would be so kind as to comment on the advantages/disadvantages of the

two techniques.

In my own experience, the Bloechl scheme gives projector and basis

functions that "look" better when you plot them in real space, but often

the Vanderbilt scheme generated functions seem to converge faster in

Fourier space (smaller ecut or gcut).  I have no idea why this is.

Usually I just use one value of rc for everything, but Marc Torrent has

shown that you can get much better agreement of the logarithmic

derivatives if you adjust the matching radii for each wave function...

2.  On the Lake Forest page, there is the comment  "In addition to

the manual prepared by Marc Torrent, notes on the method are

available. (" The link pointing to the manual is dead while the page

I can find on the abinit site would seem to be (http://www.abinit.org/

PAW/AtomPAW2Abinit-Manual-html/HolzwarthPAW.htm) which appears to be

a one page summary of how to compile the program and a couple of

input files are included with a one line of explanation of what the

input lines mean in a particular file, but there is not comment that

I could find as to the logic of how to choose parameters or even what

the naming scheme is for the different output files are. These two

examples also both use the VNCT keyword (Blochl scheme Trouiller

Martin PS).

   Thanks for some advice in advance!

For constructing the local pseudopotential, the default (no extra key

word but specify l e) is to use the traditional Troulliers-Martins scheme

at angular momentum l and energy e.   I recommend that you choose l to be

one larger l-value than that of your basis and projector functions and the

energy can be 0.   Mark Torrent has introduced some additional key words

to fine tune the local potential.    For the projectors and basis

functions the key word BLOECHL is the same as the old VNCT and VANDERBILT

is the same as the old VNCTV.   Mark Torrent has also introduced some new

options here in such as way to be backward compatible.    In trying to

explain all this, it is clear that we should try to make this easier for

the users...    some day when we find some time....   In the mean time,

thanks for your patience and we always appreciate your feedback.

                                              Natalie

Dr. Paul Fons

Nano-Optics Reseach Team

Team Leader

National Institute for Advanced Industrial Science & Technology

METI

Center for Applied Near-Field Optics Research (CANFOR)

AIST Central 4, Higashi 1-1-1

Tsukuba, Ibaraki JAPAN 305-8568

tel. +81-298-61-5636

fax. +81-298-61-2939

email: paul-fons@aist.go.jp

N. A. W. Holzwarth email: natalie@wfu.edu

Department of Physics www: http://www.wfu.edu/~natalie

Wake Forest University         voice: 336-758-5510

Winston-Salem, NC 27109-7507            fax: 336-758-6142

U. S. A.

Paul Fons

Team Leader

Nano-Optics Research Team

paul-fons@aist.go.jp

Center for Applied Near-Field Optics

National Institute of Advanced Industrial Technology

Tsukuba Central 4, Higashi 1-1-1

Tsukuba, Ibaraki Japan 305-8562

tel. +81-298-61-5635

fax. +81-298-61-2939

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