[Wien] otimization of V

[Jorissen Kevin]

First of all, for all novices (in fact, for everybody) I highly recommend reading Stefaan Cottenier's introduction to (l)APW, which can be downloaded from the wien2k web page.
 
 
 
1.  gmin is not input; it is simply given by two times the plane wave cutoff k-max (the kmax in rkmax).  The motivation is simply this : if we describe the wave function by plane waves up to exp (i kmax r), and the density by pw's up to exp (i gmax r), then, since density is wave function squared, it is reasonable to demand that gmax >= 2 * kmax.
gmax *is* input; it determines the number of plane waves used for expanding the density and potential (wien uses two basis sets : one for the basis functions, and another one for density and potential).    The time of the calculation increases for increasing gmax, but only mildly (certainly a lot milder than for increasing rkmax!)
2/  Be assured : the kgen program (which generates k-mesh) knows perfectly well what kind of structure you are using.
3/  Apparently your density is a little 'complicated' and is not well described by gmax = 14 only ...  Improving the description of the density improved your results ...  What exactly is your question?
 
 
4/  Read Stefaan's guide ...
 
 
 
Kevin Jorissen
 
EMAT - Electron Microscopy for Materials Science   (http://webhost.ua.ac.be/emat/)
Dept. of Physics
 
UA - Universiteit Antwerpen
Groenenborgerlaan 171
B-2020 Antwerpen
Belgium
 
tel  +32 3 2653249
fax + 32 3 2653257
e-mail kevin.jorissen at ua.ac.be
 

________________________________

Van: wien-admin at zeus.theochem.tuwien.ac.at namens Belkadi Amina
Verzonden: do 4-11-2004 11:40
Aan: wien at zeus.theochem.tuwien.ac.at
Onderwerp: [Wien] otimization of V


Dears WIEN users,
I have some question for the calculation of the properties of matérial:
  1- why we change the Gmin :  I have remarked that it change the time of calculation but the thing that a don't understand is what's the relation between the time of calculation and the Gmin ? for exemple for me i have use 9 at the place of 7.
   2-in the optimization of volume specially in the k-list file : why we take the k-list by default ? my structure is hexagonel 
  3- in the calculation of GGA: when i have calculated my optimization of volume, i have used firstly Gmax=14 and next i have changed to 24 because i have a probleme and with Gmax=24 i have a good result so what i want here is i want to know the reason .
i ask this questions because i am a novice in wien 
thank lot


Thanks a bunch


________________________________

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