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Dear all
I am trying to calculate electric polarization.
So, I was done some calculation.
My result:
IGPAR=1
Expectation value term: <R>ev
<R> = ( 0.00017, 0.00000, 0.00003 ) electrons Angst
Berry-Phase term: <R>bp
<R> = ( 0.04061, 0.00000, 0.00000 ) electrons Angst
+( 7.20960, 0.00000, 0.00000 ) *c
ionic term: <R>ion
<R> = ( 158.61120, 173.71000, 0.00000 ) electrons Angst


IGPAR=2
Expectation value term: <R>ev
<R> = ( 0.00006, 0.00001, 0.00007 ) electrons Angst
Berry-Phase term: <R>bp
<R> = ( 0.00000, -2.26586, 0.00000 ) electrons Angst
+( 0.00000, 13.89680, 0.00000 ) *c
ionic term: <R>ion
<R> = ( 158.61120, 173.71000, 0.00000 ) electrons Angst

IGPAR=3
Expectation value term: <R>ev
<R> = ( 0.00015, 0.00001, 0.00003 ) electrons Angst

Berry-Phase term: <R>bp
<R> = ( -0.01979, 0.00000, 0.03483 ) electrons Angst
+( -3.49547, 0.00000, 6.15063 ) *c
ionic term: <R>ion
<R> = ( 158.61120, 173.71000, 0.00000 ) electrons Angst


I have 2 question.
1) How get electric polarization from my result?
2) What means "c" and how to fine c-value?
Thanks

Best regards, Changhoon

please read the Berry phase chapter in the manual and the literature references given there

Thanks admin
I already read the berry phase chapter in the manual but there didn't have any description for c-term and how to handle for assymmetric structures.
Please show me how to calculate electric polarization from my results.
plaease please please
Thanks
Best regards, Changhoon

Dear all
As a manual, th electric polarization is <R>ev+<R>bp+<R>ion. is it right? And what means this term ?[ ( -3.49547, 0.00000, 6.15063 ) *c ]