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What is the direction of the external electric field?

Posted: Mon Aug 07, 2006 4:48 pm
by Sharani
The direction conventions followed by VASP aren't clear to me!

If I assign an external electric field of 0.1 eV/A to a system along its third lattice vector which happens to lie along the z-axis using:
EFIELD = 0.1
IDIPOL = 3
LDIPOL = .TRUE.

then will a test positive charge be pulled towards the +z or -z direction?

Also, if the dipole moment of a diatomic molecule is reported as 0.036 electron.Angstroms along the z-axis, does the negative end of the dipole point towards +z and the positive end towards -z direction?

Any information will be highly appreciated! Please help me!

Sharani.

What is the direction of the external electric field?

Posted: Tue Aug 08, 2006 6:18 am
by bandy
I think if you use LDIPOL=.T. then you should set
DIPOL=center of mass by hand. In my opinion a test positive charge feel attractive force from -z direction. As I sent before the link(http://www.quantumchemistry.net/Experie ... 2/161.html), it seems the dipole moment directions of Gaussian (for HF -1.9338 Debye or -0.38676 e A) is opposite to VASP
(0.41107 e A). But I need to know whether I am right.
<span class='smallblacktext'>[ Edited Tue Aug 08 2006, 04:42PM ]</span>

What is the direction of the external electric field?

Posted: Tue Aug 08, 2006 1:57 pm
by admin
the dipole moment in VASP is given in e*A units.