Hi,
I'd like to know what are the units of the velocities matrix elements printed out in the IBTEvel_sum.fmt file. Atomic units usually are Hartree x bohr (hbar = 1) however since energies in quantum espresso are typically expressed in Rydbergs, does that mean the velocities are printed out in Rydberg x bohr?
Thanks to anyone clarifying this
Cheers
Felix
Velocity matrix elements units
Moderator: stiwari

 Posts: 6
 Joined: Fri Jun 14, 2019 11:22 am
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Re: Velocity matrix elements units
Hi Felix,
The velocity is in Atomic Rydberg Units, "Ry*Bohr/hbar". However, in Atomic Rydberg Units, Bohr = 1 and hbar = 1, thus in order to convert velocity in "IBTEvel_sup.fmt" to SI units, you need to multiply with "factor = Ry*Bohr/hbar", where Ry, Bohr and hbar are all in SI units.
Best,
V.A.
The velocity is in Atomic Rydberg Units, "Ry*Bohr/hbar". However, in Atomic Rydberg Units, Bohr = 1 and hbar = 1, thus in order to convert velocity in "IBTEvel_sup.fmt" to SI units, you need to multiply with "factor = Ry*Bohr/hbar", where Ry, Bohr and hbar are all in SI units.
Best,
V.A.