[Pw_forum] ld1.x Questions

[Paolo Giannozzi]

On Jan 17, 2008, at 22:20 , Paul M. Grant wrote:

> I understand PP theory, but their construction, as many point out,  
> is more art than science
>

I would rather say, "more cooking than science"

> 1)      What is the purpose of the “negative ocs(nl)” settings one  
> sees frequently in the input files in /atomic_doc/pseudo_library?  
> (not covered that I can see in INPUT_LD1)
>

you didn't notice the following lines:

            Negative occupancies are used to flag unbound states;
                   they are not actually used

>   It doesn’t seem to make physical sense.

it doesn't! it is a quick and dirty (dirty more than quick) way to  
pass a piece of
information to the code about the type of state under consideration

> 2)      Why doesn’t this library contain some transition metal  
> examples?
>

...because they are by far the most difficult cases ?!?

> 3)      I’ve observed ld1.x from O-sesame (CVS) performs much  
> better the executable in the present distribution  espresso-3.2.3,  
> which yields a number of formatting errors.
>
good to hear this and not the opposite. There have been many small  
changes in the
cvs version, some of which aimed at better convergence and numerical  
stability.

> 4)      It’s stated that ld1.x output can be plotted with Grace,  
> but I see no options to produce or launch .agr files such as exists  
> in Opium.  I guess it has to be done “by hand.”
>

good guess. I think that  the statement above just means that numbers  
are in
a simple format (columns) that can be easily plotted (also with  
gnuplot).
Anybody knowing Grace is encouraged to modify the code so that it  
directly
produces .agr files

Paolo
---
Paolo Giannozzi, Dept of Physics, University of Udine
via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222