DIPOL

DIPOL = [real array]
Default: DIPOL = Template:FIXME 

Description: specifies the center of the cell in direct lattice coordinates with respect to which the total dipole-moment in the cell is calculated.

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DIPOL=Rx Ry Rz,

where R_x, R_y and R_z specify the center of the cell in direct lattice coordinates.

Mind: the calculation of the dipole requires a definition of the center of the cell, and results might differ for different positions. You should use this option only for surfaces and isolated molecules. In this case use the center of mass for the position (for surface only the component normal to the surface is meaningful).

The main problem is that the definition of the dipole 'destroys' the translational symmetry, i.e. the dipole is defined as

$\int ({\mathbf {r} }-{\mathbf {R} }_{\rm {center}})\rho _{\rm {ions+valence}}{\mathbf {r} }d^{3}{\mathbf {r} }.$

Now, this makes only sense if $\rho _{\rm {ions+valence}}$ drops to zero at some distance from $\mathbf {R} _{\rm {center}}$. If this is not the case, the values are extremely sensible with respect to changes in $\mathbf {R} _{\rm {center}}$.

Related Tags and Sections

NELECT, EPSILON, IDIPOL, LDIPOL, LMONO, EFIELD, Monopole, Dipole and Quadrupole corrections

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