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Unpaired electrons in DFT - VASP

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!<br />

<br />

¢<br />

<br />

r<br />

¢<br />

On site Coulomb repulsion<br />

L(S)DA fails to describe systems with localized (strongly correlated) d and f<br />

<strong>electrons</strong> ¡wrong one-electron energies<br />

Strong <strong>in</strong>tra-atomic <strong>in</strong>teraction is <strong>in</strong>troduced <strong>in</strong> a (screened) Hartree-Fock like<br />

manner ¡replac<strong>in</strong>g L(S)DA on site<br />

E HF¤<br />

1<br />

2 ∑<br />

γ<br />

" <br />

Uγ1 γ3 γ2γ4<br />

Uγ1γ3 γ4 γ2<br />

ˆn γ1 γ 2 ˆn γ3 γ 4<br />

determ<strong>in</strong>ed by the PAW on site occupancies<br />

ˆn γ1 γ 2¤<br />

Ψs2 m2 <br />

¢<br />

£m1<br />

and the (unscreened) on site electron-electron <strong>in</strong>teraction<br />

U γ1 γ 3 γ 2 γ 4¤<br />

m1 m3<br />

r<br />

1<br />

¢ ¢<br />

m2m4 £<br />

¢ Ψs1 £<br />

δ s1 s 2<br />

δ s3 s 4<br />

(<br />

¢ m £<br />

are the spherical harmonics)<br />

M. MARSMAN, <strong>VASP</strong> WORKSHOP, VIENNA 10-15 FEBRUARY 2003. Page 10

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