[Pw_forum] phonon branch crossing problem

[Paolo Giannozzi]

On Thursday 12 January 2006 04:24, W. YU wrote:

> I know there are some rules govening the phonon branch crossing 
> such as branches belonging to the same irrep will not cross each other.
> I don't know how PHONON manages this problem.

it doesn't. Once you have the force constants, you can calculate
eigenvalues with the correct symmetry at any q-vector. How to
connect the points into lines of well-defined symmetry is a different 
problem. There is a tool that does this for electonic band structures,
but not for phonons.

Paolo

-- 
Paolo Giannozzi             e-mail:  giannozz at nest.sns.it
Scuola Normale Superiore    Phone:   +39/050-509876, Fax:-563513 
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