Using Vasp 4.6.31 calculating a seven layer thick 1x1 Tungsten(100) surface.
Setting:
ISPIN = 2
VOSKOWN = 1
I get -82.65 eV for total energy and mag= 0.0000
For non spin polarized calculations I get -85.51 eV.
This should be the same total energy, because the system is not magnetic.
To further complicated matters I had previously done the calculation with vasp 4.5.7 and with and without the spin flags I got -85.51 eV. Using Vasp 4.5.8 with and without the spin flags I got -82.65 eV
<span class='smallblacktext'>[ Edited ]</span>
nonmagentic system gives different energy when doing spin polarized calculations.
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nonmagentic system gives different energy when doing spin polarized calculations.
Last edited by jhouze on Tue May 01, 2007 8:35 pm, edited 1 time in total.
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nonmagentic system gives different energy when doing spin polarized calculations.
please check whether it helps to decrease the compilation optimization level of xcgrad and xcspin. (some compilers need lowest optimization for these subroutines).
A very small difference (a few micro-eV) may still persist, even though the system is not magnetic
A very small difference (a few micro-eV) may still persist, even though the system is not magnetic
Last edited by admin on Tue May 08, 2007 7:19 am, edited 1 time in total.
nonmagentic system gives different energy when doing spin polarized calculations.
Thanks. It indeed was a result of compiler optimization.
Removing "-tp p6" from the pg makefile corrected the issue.
-O2 is okay.
Removing "-tp p6" from the pg makefile corrected the issue.
-O2 is okay.
Last edited by jhouze on Wed May 09, 2007 10:49 pm, edited 1 time in total.