[Pw_forum] how to calculate and plot HOMO or LUMO isosurface

[Giuseppe Mattioli]

Dear Franklin
You are making a bit of confusion between ferromagnetic systems (Fe, Ni, Co ,...), and paramagnetic 
systems (O2, among many others). Both kinds of system ARE magnetic, and generally require spin 
polarized calculations. Regarding k-points, molecules have electronic levels flat in the Brillouin 
zone (if you do not know what does such a statement mean and imply, a solid state physics textbook 
may help...). Thus, calculations of molecules do not depends on k-points, as long as the box is 
enough large to minimize the interaction between periodically repeated images of the molecule.
Solids, like ZnO, are (in a quite rough manner of speaking...) characterized by dispersed electronic 
bands instead, and require to check the convergence with respect to the k-point mesh.
HTH (another cup, please, and with cream...:-))


On Wednesday 25 July 2012 12:41:06 Franklin Zhan wrote:
> Dear Prof. Giannozzi,
> It is great to hear from you.
> In my mind, only when we are dealing with some magnetic materials
> calculation, such as Ni, iron, the spin polarization is taken into
> account. However, O2 molecule is not magnetic material, thus I do not know
> why we need to take the spin polarization into consideration.
> 
> 
> 
> Best regards,
> 
> 
> 
> 
> Franklin Zhan
> 
> Ph.D student
> School of Mechanical and Aerospace Engineering,
> Nanyang Technological University, Singapore.
> 
> > From: giannozz at democritos.it
> > Date: Wed, 25 Jul 2012 12:25:51 +0200
> > To: pw_forum at pwscf.org
> > Subject: Re: [Pw_forum] how to calculate and plot HOMO or LUMO isosurface
> > 
> > On Jul 25, 2012, at 12:20 , Franklin Zhan wrote:
> > > since O2 is not a magnetic system
> > 
> > I beg your pardon?
> > 
> > > > You seem not to be a chemist...:-)
> > > > The ground state of an O2 molecule is a triplet one, with 7 up
> > > 
> > > valence electrons and 5 down.
> > 
> > P.
> > ---
> > Paolo Giannozzi, Dept of Chemistry&Physics&Environment,
> > Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
> > Phone +39-0432-558216, fax +39-0432-558222
> > 
> > 
> > 
> > 
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> > Pw_forum at pwscf.org
> > http://www.democritos.it/mailman/listinfo/pw_forum

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   Giuseppe Mattioli                            
   CNR - ISTITUTO DI STRUTTURA DELLA MATERIA   
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