[Pw_forum] a question about a calculation on a relatively large system

[Peter Winey]

Dear Paolo, Thanks for sharing the information!

I followed your way and recompiled the code. However, the code still crashed
after the second scf iteration, same as before.

When I used damped dynamics, the code crashed after the first scf iteration.
This behavior is also same as before.

I'll sent my pwscf input file to your email address for a test (it is a
bit long to be
posted here).

I was using cp.x these days for relatively large system with no problem. But
still, it would be nice if I could run pw.x and compare the cp.x result with
the
pw.x result.

Thanks!

On 5/28/07, Paolo Giannozzi <giannozz at nest.sns.it> wrote:


> I recently encountered a similar problem (with 200 atoms; no problem
> in a smaller cell). Apparently the code crashes in the three following
> lines of update_inverse_hessian, in Modules/bfgs_modules.f90 :
>
>       inv_hess = inv_hess + 1.D0 / sdoty * &
>                  ( ( 1.D0 + ( y .dot. Hy ) / sdoty ) * matrix( s,
> s ) - &
>                   ( matrix( s, yH ) +  matrix( Hy, s ) ) )
>
> If you replace the three lines above with old-style fortran:
>
>       ydotHy = ( y .dot. Hy )
>       do j=1,n
>          do i=1,n
>             inv_hess(i,j) = inv_hess(i,j) + 1.D0 / sdoty * &
>                       ( ( 1.D0 + ydotHy / sdoty ) * s(i) * s(j) - &
>                          ( s(i)*yH(j) + Hy(i)*s(j) ) )
>          end do
>       end do
>
> it works (ifort on a PC cluster). I cannot see any good reason
> for such a behavior.
>
> By the way: in case of trouble with bfgs, one can always
> try damped dynamics.
>
> Paolo
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