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problem in parallel calculation
Posted: Sat Mar 04, 2006 9:18 am
by zhuanghl
I use completely the same input files for both the parallel and serial version of the code.There is not any problem in the serial calculation,while some warning like:
BRMIX: very serious problems
the old and the new charge density differ
old charge density: 180.09651 new 180.26392
0.571E+01
appear at some step of the parallel calculation.I don't know how so and whether it affect the final result.Thanks!
problem in parallel calculation
Posted: Tue Mar 28, 2006 8:23 am
by admin
1) please check if parallelisation affects other parameters of the run, like NBANDS: NBANDS is set to an integer multiple of the number of nodes. If the number of empty bands is too low, this may affect the results (especially if you use the RMM-DIIS algorithm for electronic convergence).
Set NBANDS to a well-defined value in INCAR and test again.
2) check whether the calculations have converged to the same final results though: Mixing does not affect the converged results themselves, however it may change the speed of convergence.
3) if NBANDS seems reasonable in the parallel run, and the results differ for exactly the same input, I think this is an indication that something may be wrong with your parallel environment. Try to decrease the compiler optimisation flags re-compile VASP and do another test run. If this does not work as well, ask the people who installed the computers to make checks of the hardware / compiler installation.
problem in parallel calculation
Posted: Thu Jul 12, 2007 5:46 am
by mindflying
Hi, zhuanghl,
How did you get the problem solved?
I got the same problem when compiling parallel vasp, and serial vasp has no problem.
The machine is opteron. I can compile the parallel vasp smoothly, though with several annoying messages as follows:
ifort: command line warning #10121: overriding '-xO' with '-xW'
ifort: command line remark #10148: option '-tp' not supported
fortcom: Warning: elpol.f90, line 693: The statement following this DEC loop optimization directive must be an iterative do-stmt, a vector assignment, an OMP pdo-directive, or an OMP parallel-do-directive.
!DIR$ IVDEP
------^
In fact I got the "BRMIX" problem with serial version when using setting as follows:
FFT3D = fftw3d.o fft3dlib.o /usr/local/lib64/libfftw3.a
, but it's ok when I swithed to the other setting:
FFT3D = fft3dfurth.o fft3dlib.o
Thanks.