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Quantities of interest
Once at self-consistency the bandstructure energy can be calculated by occupying the energy levels corresponding to
or expanded in the implicit basis:
|
(22) |
where the quantities without indices are matrices to be multiplied as such.
A more smoothly varying quantity is the first order energy:
|
(23) |
Together with the second order energy,
|
(24) |
the classical term
and
the electrostatics contribution combine to form the total energy.
The corresponding forces are given by:
|
(25) |
Where ,
and
are 3D vectors.
Additionally the pressure may be obtained through the radial derivatives:
|
(26) |
NB There is no magnetic contribution to the forces.
Next: Periodicity
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DP 2013-08-01