[Pw_forum] converged to wrong magnetic state of hcp cobalt in Opteron

[wlyim at puccini.che.pitt.edu]

Dear Axel,

Thanks for your advice.

I have compiled pwscf.2.1.4 using EM64T Version 9.0 with MKL 8.0.1. Again, 
the electronic structure went to the wrong state.
==================================================
INTEL EM64T result:
!    total energy              =  -148.81668356 ryd
     estimated scf accuracy    <        2.0E-12 ryd

     band energy sum           =    15.05020564 ryd
     one-electron contribution =     6.02718174 ryd
     hartree contribution      =    21.83280277 ryd
     xc contribution           =   -65.85608487 ryd
     ewald contribution        =  -110.85073891 ryd
     correction for metals     =     0.03015572 ryd

     total magnetization       =     3.75 Bohr mag/cell
     absolute magnetization    =     4.14 Bohr mag/cell
=======================================================

It seemed to me that in this chemical system, the energy is constantly
shifted by 0.06 Ry when compared to Origin result. I pick up the first 
iteration step for comparison:
================================================
Origin:
     iteration #  1     ecut=    30.00 ryd     beta=0.70
     Davidson diagonalization (with overlap)
     ethr =  1.00E-02,  avg # of iterations =  4.2

     npt with rhoup < 0:        2, npt tot    20736,      0.01 %

     npt with rhoup < 0:        2, npt tot    20736,      0.01 %

     total cpu time spent up to now is     15.75 secs

     total energy              =  -147.96340174 ryd
     estimated scf accuracy    <     2.11694003 ryd

     total magnetization       =     5.92 Bohr mag/cell
     absolute magnetization    =     5.97 Bohr mag/cell
=================================================
Opteron(PGI) or INTEL(EM64T) result:
     iteration #  1     ecut=    30.00 ryd     beta=0.70
     Davidson diagonalization (with overlap)
     ethr =  1.00E-02,  avg # of iterations =  4.1

     npt with rhoup < 0:        2, npt tot    20736,      0.01 %

     npt with rhoup < 0:        2, npt tot    20736,      0.01 %

     total cpu time spent up to now is     30.39 secs

     total energy              =  -147.90474844 ryd
     estimated scf accuracy    <     2.13792299 ryd

     total magnetization       =     5.95 Bohr mag/cell
     absolute magnetization    =     6.00 Bohr mag/cell
======================================================

At the initial stage, I would expect that the "total energy" are quite 
similar calculated in two different platforms. However this is not the 
case. Origin's energy is about 0.06 Ry lower than that in Opteron. And 
such a difference was kept till the end. I can't imagine what reasoned for 
this. On the other hand, platinum is free of this problem.

Is it due to different fft treatments in Origin and Linux machines? Or 
code/library problem?

Many thanks in advance.

Best regards,
William

On Thu, 13 Apr 2006, Axel Kohlmeyer wrote:

> On Thu, 13 Apr 2006 wlyim at puccini.che.pitt.edu wrote:
> 
> WL> Dear all,
> 
> dear william,
> 
> please check the mailing list archives. the PGI compilers version 5.x
> are _known_ to miscompile several parts of quantum espresso (and not
> only that code, i know of several other DFT codes as well).
> the same is true for quite few SGI compilers...
> if you can, please try with the intel (EM64t) compilers on opteron
> to check, whether it is still going to the wrong state. it additionally
> may depend on the kind of BLAS/LAPACK library you are using. there are 
> a few bugs in several of them as well.
> 
> best regards,
>   axel.
> 
> WL> 
> WL> I did a test on crystalline hcp cobalt by pwscf.2.1.4, both on Opteron
> WL> (pgf90 5.2-4, lam 7.1.1) and Origin. I found that the calculation 
> WL> converged to a wrong magnetic state in Opteron, while the calculation in 
> WL> Origin was okay.
> 
> [...]
> 
> WL> I used the PBE uspp as provided in pwscf website. On the other hand, I 
> WL> have also tried the calculations on platinum, which is a closed-shell 
> WL> system, and I got essentially the same results from Opteron and Origin.
> WL> 
> WL> Does anyone experience a similar thing? I will be appreciated if someone 
> WL> can give a help hand.
> WL> 
> WL> Many thanks in advance!
> WL> 
> WL> I am also attaching the input file at the bottom of this meesage.
> WL> 
> WL> regards,
> WL> William
> WL> 
> 
> [...]
> 
>