Hi,
I think I have seen H2 dissociate as well, but I forgot the details.
I note you do not use set_initial_magnetic_moments. Have you tried to set
the initial_magnetic_moments to e.g. (0., 0.), (1., 1.) and (1., -1.)?
What is the MAGMOM-tag in the INCAR? The vasp default is MAGMOM = 1 1
(which you probably do not want).
Best Regards,
Heine
> Hi,
>
> you should check the occupation numbers:
> http://cms.mpi.univie.ac.at/vasp-forum/forum_viewtopic.php?4.490
>
> Best regards,
>
> Marcin
>
> On 04/12/2013 09:41 PM, Sashank Kasiraju wrote:
> > Dear ASE/VASP users,
> >
> > This is my first query, so if I miss something or if I am unclear
> > please bear with me. I am a relatively new vasp user.
> >
> > I was trying to do this simple calculation for finding the potential
> > energy of H2 Molecule. I got 2 different results with and without
> > spin-polarized calculation. I am using "/vasp.5.3.3 18Dez12 (build Jan
> > 17 2013 09:57:53)/"
> >
> > 1. When ispin=1 (non-spin polarized) , the bond length of the relaxed
> > configuration was around the 0.747 A which is close to the
> > experimental value with a potential energy of about (-7.04 ev)
> > 2. When ispin=2 (spin-polarized), the bond length of relaxed
> > structure was 3.801 A, i.e. the hydrogen atoms in the molecule
> > moved apart and exist as 2 separate H atoms with the potential
> > energy of about (-2.47 ev)
> >
> > You can find the python script below. Both the cases have the same
> > python script (except for the presence/absence of ispin tag i.e. case
> > 1: no ispin tag, case 2: ispin=2). I used the ibrion=2 tag for ionic
> > relaxation. I will be happy to provide any other information/outputs
> > if required. Can you please let me know why this is happening? Or if I
> > am going about it totally wrong?
> >
> > Thanks in advance!
> >
> > *Script: *
> >
> > from ase.visualize import view
> > from ase.calculators.vasp import Vasp
> > from ase.io <http://ase.io> import write
> > from ase.structure import molecule
> > from ase.io <http://ase.io> import read
> > import os.path, os
> >
> > os.environ['VASP_EXEC']='vasp_std' # define the vasp executable here
> >
> > file=open('Hydrogen_Energy.txt','a')
> > name = 'H2_Energy'+ '.traj'
> > atoms= molecule('H2')
> > atoms.center(vacuum=10)
> > calc=Vasp(xc='PBE',
> > gga='RP',
> > ibrion=2,
> > lscalapack=False,
> > nsw=500,
> > nelm=200,
> > ediffg=-0.01,
> > prec='Accurate',
> > encut=540,
> > ediff=1E-6,
> > kpts=(1,1,1),
> > ismear=0,
> > ispin=2,
> > sigma=0.01,
> > lwave=False,
> > lcharg=False,
> > ialgo=48,
> > lreal='False',
> > idipol=4,
> > ldipol=True,
> > dipol=(0.5,0.5,0.5),
> > gamma=True,
> > npar=2)
> > atoms.set_calculator(calc)
> > e = atoms.get_potential_energy()
> > write(name, atoms)
> > file.write(str(e)+'\n'+'In (ev)')
> > file.close()
> >
> > Warm Regards,
> > Sashank.
> >
> > --
> > Regards,
> > Sashank Kasiraju,
> > PhD Student,
> > Dept. of Chemical Engineering,
> > University of Houston.
> >
> >
> > _______________________________________________
> > ase-users mailing list
> > ase-users at listserv.fysik.dtu.dk
> > https://listserv.fysik.dtu.dk/mailman/listinfo/ase-users
>
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