[Pw_forum] Question about Example10

[lan haiping]

Hi All, Happy new year !

 I have  a question about berry phase calculation for born effetive charge
implemented in espresso.
 I just run a series calculation with the script of example10 by modifying
parameters , while i can not obtain satisfactory results for  O sites.
Actually, I could obtain  born effective tensor of Pb site about  3.9
-3.92 e whenever
i increase ecutoffrho , conv_thr or use denser kmesh..
But the born effective tensor of O sites , i.e . the three diagonal elements
are not consistent with the result  of Zhong et al (PRL.72.3618).  The
values i obtained are  -1.98 , -5.85, -1.90e  respectively for 3 different
directions.

The procedure for me to calculate this quantity of O sites is really
followed  that of Pb  in Example10.  Would you please give me some hints for
this problem ?

Regards
hai-ping
-- 
Hai-Ping Lan
Department of Electronics ,
Peking University , Bejing, 100871
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