[Pw_forum] Phonon branch enumeration
Jeffrey Mullen
jtmullen at ncsu.edu
Tue Mar 10 01:34:01 CET 2009
Greetings
I am testing electron-phonon interaction calculations with graphene and
have encountered a problem enumerating the resulting phonon branches.
When I run the ph.x calculation at the q(0 0 0), the code calculates 4
representations:
Representation # 1 modes # 1 2
Representation # 2 mode # 3
Representation # 3 mode # 4
Representation # 4 modes # 5 6
When the values for omega are calculated, the results are:
**************************************************************************
omega( 1) = -1.119851 [THz] = -37.354451 [cm-1]
omega( 2) = -1.016557 [THz] = -33.908905 [cm-1]
omega( 3) = -1.016557 [THz] = -33.908905 [cm-1]
omega( 4) = 25.882237 [THz] = 863.344237 [cm-1]
omega( 5) = 40.051667 [THz] = 1335.988701 [cm-1]
omega( 6) = 40.051667 [THz] = 1335.988701 [cm-1]
**************************************************************************
with the following mode symmetries:
Mode symmetry, D_6h(6/mmm) point group:
omega( 1 - 1) = -37.4 [cm-1] --> A_2u I
omega( 2 - 3) = -33.9 [cm-1] --> E_1u I
omega( 4 - 4) = 863.3 [cm-1] --> B_2g
omega( 5 - 6) = 1336.0 [cm-1] --> E_2g R
My question is one of ordering. How do I extract which omega(##)
corresponds to which representation/mode?
Thanks
Jeff Mullen
North Carolina State University
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