[Pw_forum] Pw_forum] Shift of Energy

[Eduardo Ariel Menendez Proupin]

Hi Pari,

I think you should read this book.

Density functional theory: a practical introduction  David S. Sholl,Janice
A. Steckel

http://books.google.com/books?id=Q8iNmtswLWYC&printsec=frontcover&dq=Janice+Steckel++Sholl&source=bl&ots=BBHL-SfWoi&sig=HLO4FmyafC7bKh22C0Qf1353Lug&hl=es&ei=KfaZTaajFImatwfQ95iVDA&sa=X&oi=book_result&ct=result&resnum=1&ved=0CBcQ6AEwAA#v=onepage&q&f=false

72/8
9.00000000000000000000
694/9
77.11111111111111111111
694/9-76.276
.83511111111111111111
So, where does the 7 Ry difference arise?

Best regards

Eduardo Menendez
Departamento de Fisica
Facultad de Ciencias
Universidad de Chile
Phone: (56)(2)9787439
URL: http://fisica.ciencias.uchile.cl/~emenendez


>
>
> ---------- Mensaje reenviado ----------
> From: pari shok <parishok at gmail.com>
> To: pw_forum at pwscf.org
> Date: Mon, 4 Apr 2011 10:32:53 -0400
> Subject: [Pw_forum] Shift of Energy
> Dear All,
> Thank you very much for your help.
> Please let me ask my final question w.r.t DOS shift of energy of SiC
> supercell.
> The total energy of the 8-atom cell of SiC is: -76.276 Ry, while that of
> 72-atom SiC is -694 Ry. Neglecting almost -7 Ry, the total energy is scaling
> accordingly.
> However, I still see the shift of energy in DOS diagram of two slabs (the
> max and min of bandgap shifts, although the gap is almost 2.1 eV for both
> 4H-SiC slabs). I was wondering whether this shift of energy is inevitable or
> it is as the result of my input file.
> I kept k points (w.r.t. crystal), and cut off energy the same for both
> structures. Should I scale the cut off energy as well. If positive, is there
> any relation between scaling the cell and cut off energy.
> As you know, I need to find a reference for my further calculations.
> I really really appreciate your help.
> Yours
> P Shok
>
>
> --
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