Hello,
I have performed a phonon calculation using ph.x. During the scf calculation
(prior to using ph.x), the ATOMIC_POSITIONS is in Bohr units. I am also using
ibrav = 0 and an orthorhombic crystal system. After ph.x, I have used dynmat.x
to apply asymmetric sum rule and ?get the new phonon eigenvalues and
eigenvectors. The output of dynmat.x has the following format:?
? ? ?omega(12) = ? ? ? 1.305968 [THz] = ? ? ?43.562397 [cm-1]
?( -0.052340 ? 0.000000 ? ?-0.021008 ? 0.000000 ? ? 0.002346 ? 0.000000 ? )
?( -0.003841 ? 0.000000 ? ?-0.009204 ? 0.000000 ? ? 0.053835 ? 0.000000 ? )
?( ?0.014655 ? 0.000000 ? ?-0.015822 ? 0.000000 ? ? 0.085998 ? 0.000000 ? )
?( -0.013791 ? 0.000000 ? ?-0.035434 ? 0.000000 ? ? 0.066956 ? 0.000000 ? )
While the units of omega is evident, the unit of eigenvectors is not clear. I
wonder what is the unit of eigenvectors ?
The atomic position have the following units:
ATOMIC_POSITIONS { alat | bohr | crystal | angstrom }
Do the phonon eigenvectors have the same units as atomic positions or they have
one particular unit always ? If it is one particular unit then what it is ? I
noticed that the dynamical matrix is written in cartesian axes (I assume it
means ?in the units of alat).?
Thanks,
David
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