[Pw_forum] ld1.x normalization and overlap integrals

Paolo Giannozzi giannozz at nest.sns.it
Sun Aug 27 21:58:57 CEST 2006

On Saturday 26 August 2006 19:36, Eduardo Ariel Menendez P wrote:

> Doing an all-electron calculation with atomic code (ld1.x) I can read
> from the output that the overlap integrals are not zero
> [...] 
> In my case, the overlap integrals are 0.000000 if rel=0 or rel=2,
> and give the above numbers if rel=1.

if rel=0 or rel=2 the overlap integrals are respectively calculated 
between atomic orbitals (non-relativistic case: Schroedinger 
Kohn-Sham equation) or between spinors ((fully relativistic case:
Dirac-like equation from the relativistic extension of DFT).

In the rel=1 (the so-called scalar relativistic case) only the main
relativistic corrections are evaluated and only the major component 
of the spinor is actually calculated. In this case the "overlap" integrals
are missing the contribution of the minor components.

Paolo Giannozzi             e-mail:  giannozz at nest.sns.it
Scuola Normale Superiore    Phone:   +39/050-509876, Fax:-563513 
Piazza dei Cavalieri 7      I-56126 Pisa, Italy

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