[CPMD-list] Ewald corrected

[Audrius Alkauskas]

 Dear colleagues

 I am writing a small molecular mechanics program, and wanted to implement
 Ewald summation. The numbers I got were not good, so I was looking for some
 mistake. In the article of Hutter and Marx ( in "Modern Methods and
 Algorithms of Quantum Chemistry") they say that Fourier transform of a
 Gaussian charge distribution A \exp (-\frac{r^2}{a^2}) is B \exp
 (-frac{1}{2} G^2 a^2) but according to my calculations it surely
 must be B \exp (-frac{1}{4}G^2 a^2)  (one-fourth instead of
 one- secondth). Now my code is working properly. Is it some trick or is it
 something I don't understand or is it just a mistake in the book?

 Thank you

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Audrius Alkauskas, PhD student
Condensed Matter Theory Group & NCCR for Nanoscale Science
Institute of Physics, University of Basel, Switzerland
http://monet.physik.unibas.ch/~audrius/
Tel.: +41-61-267-3708
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