Dear Dr. Clavijo, Thank you for your helpful information. My concern is about the setting of noncolin variable. My question is: If I use scalar-relativistic pseudopotentials for all atoms of CH3NH3PbI3, should I use noncolin=.TRUE or noncolin=.FALSE? Now I am not quite whether scalar-relativistic pseudopotentials directly include the nonlinear calculation.
Regards, MC Wang On Thu, Mar 3, 2016 at 8:42 PM, Josue Itsman Clavijo Penagos < [email protected]> wrote: > Dear Mingchao Wang, as far as i know, the best case is to use > Pseudopotentials of the same kind for all atoms, and preferably > full-relativistic, so the spin-orbit coupling can be accurately taken into > account, since it its known that Eg calculated without relativistic > spin-orbit coupling is , although not very different that the > no-relativistic calculated one due to cancelling over- and under- > estimation issues in non-relativistic pseudopotentials, not a good obtained > one. Long words short: you're getting a Eg value from a not so much > physically accurate calculation framework. > > On the other hand, you not need to use H atoms to calculate Band > Structure, since their contribution is only in the deep levels of valence > and conduction bands (not near the band gap), unless you are into studying > deep band structure actually. > > Finalliy, I think that noncolin=true is a must for spin-orbit calculations > in pw.x , but i'm not 100% sure if that's true for an hybrid > inorganic-organic system such as a CH3NH3PbI3 unit cell crystal at any > temperature and crystal system of those this material can form. > > Anyway, Would you mind to put your pw input file, so i can compare my > calculations with yours, since i'm currently working on the same system? > that would be very very helpful to me and for others fellows in the forum > and all would help you more and better, also. > > Best regards, > > Josué Clavijo, PhD. > Assistant Professor > Universidad Nacional de Colombia > _______________________________________________ > Pw_forum mailing list > [email protected] > http://pwscf.org/mailman/listinfo/pw_forum
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