[Pw_forum] Binding energy of P-dpoed Si

[Vo, Trinh]

Dear PWSCF,

I plan to calculate the impurity binding energy of P-doped Si bulk.  I searched literatures, and I see people used mainly Effective mass approximation (EMA)  (or used first principles to obtain potential, then used EMA).  According these papers, the binding energy is determined as the difference between impurity level and the minimum of the conduction band.  I also found other papers by Chelikowsky et al (Nano Letters 8, 596 (2008), PRL 92, 46802 (2004)), who calculated binding energy of P-doped nanocrytals by calculating the ionization energy, I_d, of SiP system with one electron removed, and the affinity,  A_p, of the pure Si system with one electron added.  The binding energy is determined as:
E_b = I_d - A_p

I saw problems when I want to calculate E_b by Chelikowski's method, since that method only works for non-extensive system such as nanocrystals.  For P-doped Si bulk (with periodic boundary condtion), I cannot calculate I_d and A_p (or there may be a way that I do not know).  If using DFT, I do not know (using espresso code) how I define the binding energy properly.  Is the definition of binding energy as used in EMA is still valid?

I appreciate very much if you know an alternative to calculate binding energy by using DFT.

Thank you,

Trinh
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