[CPMD-list] discrepant total energies

[Axel Kohlmeyer]

On Wed, 11 May 2005, Kozin, I (Igor) wrote:

IK> Hello,

dear igor,

IK> I was recently pointed out to the difference in 
IK> the initial total energies computed using different
IK> compilers. Particularly for cpmd-test/std/wat32/inp-1
IK> IBM           -539.79205456 A.U.  (as provided)
IK> Intel         -539.79205456 A.U.
IK> PathScale     -539.79205494 A.U.
IK> PGI           -534.04296070 A.U.
IK> 
IK> There is not much difference using Intel or PGI
IK> on 32- or 64-bit platforms or using various compiler
IK> options. Fortunately everything converges nicely to 
IK> -551.05084246 A.U.
IK> But still the question is why the initial PGI value
IK> is so different?

the pgi compiler is known to occasionally miscompile stuff.
i have seen it with other plane-wave pseudopotential
packages as well. in this case it seems to be code to compute
the slater orbitals for the inital guess.
there was another post concerning this issue recently in
combination with vanderbilt pseudopotentials. please check 
the mailing list archive. i did a cross-check of that
specific example and found, that PGI compiles correctly
in case of turning off the optimization (-O0). it would
be useful to know, _which_ parts of cpmd are actually 
miscompiled, so we can take care of it in the PGI configuration
files.

best regards,
	axel.


IK> 
IK> Many thanks in advance,
IK> Igor
IK> 
IK> I. Kozin  (i.kozin at dl.ac.uk)
IK> CCLRC Daresbury Laboratory
IK> tel: 01925 603308
IK> http://www.cse.clrc.ac.uk/disco
IK> 
IK> _______________________________________________
IK> CPMD-list mailing list
IK> CPMD-list at cpmd.org
IK> http://cpmd.org/mailman/listinfo/cpmd-list
IK> 
IK> 

-- 

=======================================================================
Dr. Axel Kohlmeyer   e-mail: axel.kohlmeyer at theochem.ruhr-uni-bochum.de
Lehrstuhl fuer Theoretische Chemie          Phone: ++49 (0)234/32-26673
Ruhr-Universitaet Bochum - NC 03/53         Fax:   ++49 (0)234/32-14045
D-44780 Bochum  http://www.theochem.ruhr-uni-bochum.de/~axel.kohlmeyer/
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If you make something idiot-proof, the universe creates a better idiot.