[Pw_forum] Benchmarking QE 4.1

[Lorenzo Paulatto]

On Wed, 20 Jan 2010 20:04:40 +0100, Marcos Veríssimo Alves  
<marcos.verissimo.alves at gmail.com> wrote:
  The time bewteen the end of
> the initialization of the calculation (starting mode="from scratch")
> and end of the first calculation step are much longer than the typical
> times for the subsequent davidson diagonalization steps (between 4-5
> times longer):

Dear Marcos,
when performing the first diagonalization the initial trial wavefunctions  
used by the algorithm are just a superposition of atomic wavefunctions,  
which are only a very rough estimate of the eigenvaleus. On subsequent  
steps the initial trial wavefunctions are the ones from the previous scf  
step, which are usually quite a good estimate. If after finishing the  
calculation you restart it from scratch, but setting startingwfc='file',  
you should find that now the first diagonalization step is as fast as the  
subsequent ones.

best regards


-- 
Lorenzo Paulatto

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