DIPOL by default
Posted: Thu Jun 07, 2012 7:58 pm
Hello everyone:
I am doing dipole moment calculation for defects in solids using VASP 4.6 and have some troubles to understand the DIPOL tag if it was set by default.
DIPOL is the center of net charge distribution, which is also taken as the reference point of calculating dipole moment.
The manual says if the flag is not set, VASP determines, where the charge density averaged over one plane drops to a minimum and calculates the center of the charge distribution by adding half of the lattice vector perpendicular to the plane where the charge density has a minimum. In manual section 6.58, it also mentions I should try different values of DIPOL and the one giving the minimum correction should be the correct DIPOL.
Now for my understanding, the default DIPOL, if it is really reasonable, should give a minimum dipole moment. My question is: does center of net charge distribution equals to the position giving the minimum dipole moment? If not, then choosing the DIPOL as default may give greater dipole moment correction, right? Does that means I have to set the DIPOL by hand to minimize it.
Thank you so much for any help.
I am doing dipole moment calculation for defects in solids using VASP 4.6 and have some troubles to understand the DIPOL tag if it was set by default.
DIPOL is the center of net charge distribution, which is also taken as the reference point of calculating dipole moment.
The manual says if the flag is not set, VASP determines, where the charge density averaged over one plane drops to a minimum and calculates the center of the charge distribution by adding half of the lattice vector perpendicular to the plane where the charge density has a minimum. In manual section 6.58, it also mentions I should try different values of DIPOL and the one giving the minimum correction should be the correct DIPOL.
Now for my understanding, the default DIPOL, if it is really reasonable, should give a minimum dipole moment. My question is: does center of net charge distribution equals to the position giving the minimum dipole moment? If not, then choosing the DIPOL as default may give greater dipole moment correction, right? Does that means I have to set the DIPOL by hand to minimize it.
Thank you so much for any help.