[Pw_forum] wrong para?

[B. Yanchitsky]

Dear users,

There is a strange thing in parallel version of pw.x.
Parallel version running on 2 processors (cores) (dual-core pentium-d, mpich, npool=2)
and the same pw.x code running on single processor (core) produce different results.
As example
First iteration for 2 processors
      total energy              =  -154.98769308 ryd
First iteration for 1 processor
      total energy              =  -154.98786918 ryd


2 processors
!    total energy              =  -155.02553035 ryd
1 processor
!    total energy              =  -155.02553039 ryd

Forces are also different
2 processors
      atom  61 type  1   force =    -0.00042175   -0.00024350    0.00000000
1 processor
      atom  61 type  1   force =    -0.00042242   -0.00024388    0.00000000


My configuration is ifort 9.0 + mkl 8.0.2.
Could you give any ideas/propositions?
Any additional info will be sent on your request from my side.

Regards,
Bogdan Yanchitsky

Institute of Magnetism
Vernadsky Blvd., 36-b
03142  Kiev
UKRAINE

Tel. (+380-44) 444 34 20
Fax. (+380-44) 444 10 20