[Q-e-developers] Fwd: hello from CYRen in Taiwan, who develops USPP codes

[Paolo Giannozzi]

Does anybody know where the preconditioning used in conjugate-gradient
diagonalization come from?

P.
---------- Forwarded message ----------

I found that the preconditioning for conjugate gradient searching in
espresso-5.4.0 is something like
h_diag(ig)=1+g2kin(ig)+sqrt(1+(g2kin(ig)-1)**2)
in c_band.f90
where g2kin(ig) is |k+G|^2, as defined in g2_kin.f90

I understood the preconditioning by Teter  Payne, and Allan. May you
please tell me why QE choose the form above? or any references for
that.
---------- Forwarded message ----------

-- 
Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222