[CPMD-list] on RAGGIO and KPOINTS units

[Ari P Seitsonen]

Dear Dr Menendez Proupin,

  Just to add to Axel's answer some details.

 1) This is an "unphysical" parameter used in the Ewald summation; it
    must not be too large or too small in order to achieve convergence
    both in the reciprocal and real space terms; a value around the 1.0
    is good. More information on page 49ff in the review of Marx and
    Hutter, http://www.fz-juelich.de/nic-series/Volume1/marx.pdf

 2) Indeed the units are 2pi/a, there's no sense neglecting the 2pi.
    'alat' is, to the best of my knowledge, always CELLDM(1); if you
    provide the basis vectors explicitly, this is the length of the first
    vector (A1).

    Silly Greetings, ;)

       apsi

-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-
 Ari Paavo Seitsonen / Ari.P.Seitsonen at iki.fi / http://www.iki.fi/~apsi/
 Tel +41 1 635 44 97 / Fax +41 1 635 68 38 / GSM +41 79 719 09 35      
 Anschrift: Physikalisch Chemisches Institut (PCI), Universität Zürich (UniZh)
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 Address:   Schweiz / Svizzera / Suisse / Svizra / Switzerland

On Thu, 9 Sep 2004, Eduardo Ariel Menendez P wrote:

> Hello everybody,
> 
> Just two silly questions,
> 
> 1. What is the meaning of
> "the width of the ionic charge distribution" [i.e. the keyword RAGGIO]?
> 
> 2. What are the units of the KPOINTS when they are given in cartesian
> coordinates. The manual says "units 1/a". What is "a" for a non cubic
> lattice? Is there any option to give the KPOINTS in units of 2pi/a  ?
> 
> Thank you,
> 
> Eduardo A. Menendez Proupin
> Department of Physics
> Faculty of Science
> University of Chile
> Las Palmeras 3425
> Ñuñoa, Santiago
> Chile
> Phone: 56+2+678 74 11
> http://fisica.ciencias.uchile.cl/~emenendez/
> 
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