[Pw_forum] Upper estimation of lattice parameter by LDA pseudopotential -regarding

[Mostafa Youssef]

Dear  Suresh,


I think the reason is the Ti pseudopotential.  This one has 4 valence electrons and freezes the rest.  This leads to larger ionic sizes and overestimation of the lattice constant.  Allowing more Ti valence electrons, means further relaxation for the outer electronic shell and better adoption to the crystal environment.  Try  a Ti PP that has 12 electrons.  Pslib from which you obtained this one, has also ultrasoft pseudos with 12 electrons.



Regards,
Mostafa
MIT
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