NaF Berry Phase calculation
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NaF Berry Phase calculation
Dear VASP users and experts,
In "Berry Phase Type calculation" on NaF, if I use IGPAR=1, I have got:
For undistorted case:
-----------------------
e<r>_ev=( 0.00000 0.00000 0.00000 ) e*Angst
e<r>_bp=( 0.00000 0.00000 0.00000 ) e*Angst
Total electronic dipole moment: p[elc]=( 0.00000 0.00000 0.00000 ) e*Angst
ionic dipole moment: p[ion]=( 2.25510 2.25510 2.25510 ) e*Angst
----------------------------------------
For distorted case:
----------------
e<r>_ev=( 0.00000 0.00000 0.00004 ) e*Angst
e<r>_bp=( 0.00000 0.18033 0.18033 ) e*Angst
Total electronic dipole moment: p[elc]=( 0.00000 0.18033 0.18037 ) e*Angst
ionic dipole moment: p[ion]=( 2.25510 2.25510 1.93939 ) e*Angst
--------------------------------------
From these above two set of data, I can have "Born Effective Charge (BEC)": 0.9961864219 elect., consistent with manual.
BUT, If use IGPAR=3, I have got:
For distorted case, (undistorted case as same before):
------------------
e<r>_ev=( 0.00000 0.00000 0.00004 ) e*Angst
e<r>_bp=( -0.18033 -0.18033 0.00000 ) e*Angst
Total electronic dipole moment: p[elc]=( -0.18033 -0.18032 0.00004 ) e*Angst
ionic dipole moment: p[ion]=( 2.25510 2.25510 1.93939 ) e*Angst
-----------------------------------
If you look into the Total Electronic dipole moment, it has BP contribution, with same mag. but different sign, and If you use it for BEC calculation, it will be: -14.9967481117 elect., not same than before! How do I explain?
Thank you very much for your comments,
Tilak
In "Berry Phase Type calculation" on NaF, if I use IGPAR=1, I have got:
For undistorted case:
-----------------------
e<r>_ev=( 0.00000 0.00000 0.00000 ) e*Angst
e<r>_bp=( 0.00000 0.00000 0.00000 ) e*Angst
Total electronic dipole moment: p[elc]=( 0.00000 0.00000 0.00000 ) e*Angst
ionic dipole moment: p[ion]=( 2.25510 2.25510 2.25510 ) e*Angst
----------------------------------------
For distorted case:
----------------
e<r>_ev=( 0.00000 0.00000 0.00004 ) e*Angst
e<r>_bp=( 0.00000 0.18033 0.18033 ) e*Angst
Total electronic dipole moment: p[elc]=( 0.00000 0.18033 0.18037 ) e*Angst
ionic dipole moment: p[ion]=( 2.25510 2.25510 1.93939 ) e*Angst
--------------------------------------
From these above two set of data, I can have "Born Effective Charge (BEC)": 0.9961864219 elect., consistent with manual.
BUT, If use IGPAR=3, I have got:
For distorted case, (undistorted case as same before):
------------------
e<r>_ev=( 0.00000 0.00000 0.00004 ) e*Angst
e<r>_bp=( -0.18033 -0.18033 0.00000 ) e*Angst
Total electronic dipole moment: p[elc]=( -0.18033 -0.18032 0.00004 ) e*Angst
ionic dipole moment: p[ion]=( 2.25510 2.25510 1.93939 ) e*Angst
-----------------------------------
If you look into the Total Electronic dipole moment, it has BP contribution, with same mag. but different sign, and If you use it for BEC calculation, it will be: -14.9967481117 elect., not same than before! How do I explain?
Thank you very much for your comments,
Tilak
Last edited by tilak on Fri Jan 17, 2014 5:14 pm, edited 1 time in total.
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Re: NaF Berry Phase calculation
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