[Pw_forum] Alignment Procedure of Energy level in Different Systems

[idoldog]

Dear PWSCF users,

recently, i was puzzled by an issue about energy level of different systems. what i studied was doped perovskite-type crystal. because there were two elements i used to dope, i got some different systems. For example, in La-doped system, it must contain the element La, however, in Mo-doped system, there is Mo dopant atoms instead of La impurity. Some scientists say its zero energy is arbitrariness, so one must preform some alignment procedure.

so my question is: 

1. what is meaning about the Fermi level given by PWSCF code directly?  in the output file, it might look like this:
----------------------------------------------------------------------       
     the Fermi energy is    12.3654 ev

!    total energy              = -2320.88829157 Ry
     Harris-Foulkes estimate   = -2320.88829157 Ry
     estimated scf accuracy    <        7.7E-10 Ry
---------------------------------------------------------------------

2. i have got a lot of Fermi level with different systems. Can they compare with each other? or should i preform some alignment procedure?  how to do?
Someone tell me that one usually treat the top of valence band  each systems  as zero energy.  is that right?

Look forward to your reply and ANY SUGGESTION IS APPRECIATED.



Li Fei
2010-04-13
 	

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硕士研究生    李飞
南开大学新催化材料科学研究所
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