average phonon frequencies
Posted: Fri Aug 30, 2019 4:12 pm
Dear EPW community
I'm currently running some calculations with EPW 5.1, aiming to study the electron-phonon interaction in some simple systems. As part of the outputs I'm trying to determine are the average phonon frequencies <w> and the logarithmic average phonon frequencies w_log. To perform the calculations, I'm using the following setting:
What I'm not sure is wether these logavg and l_a2f quantities are the ones I'm seeking to determine.
I read in some previous post that the logavg should be the logarithmic average phonon frequency, displayed in Ry. My next step was to try to convert it to Kelvin: logavg[K]=logavg[Ry]*157887=1103K. By entering this value into the McMillan formula, together with lambda=0.3208 and mu=0.1, it results in a crictical temperature of arround 1K, very different from the result of 5.9K.
So my main questions at this point are who are these two quantities displayed above the critical temperatures, and in which units are they being displayed.
Thanks in advance for any assistance
Fbio Costa
I'm currently running some calculations with EPW 5.1, aiming to study the electron-phonon interaction in some simple systems. As part of the outputs I'm trying to determine are the average phonon frequencies <w> and the logarithmic average phonon frequencies w_log. To perform the calculations, I'm using the following setting:
Code: Select all
...
elecselfen = .true.
phonselfen = .true.
a2f = .true.
...
What I'm not sure is wether these logavg and l_a2f quantities are the ones I'm seeking to determine.
Code: Select all
===================================================================
Eliashberg Spectral Function in the Migdal Approximation
===================================================================
lambda : 0.3208895
lambda_tr : 0.4251001
Estimated Allen-Dynes Tc
logavg = 0.0069899 l_a2F = 0.4189137
mu = 0.10 Tc = 5.969107220843 K
mu = 0.12 Tc = 3.715758994450 K
mu = 0.14 Tc = 2.096133038087 K
mu = 0.16 Tc = 1.035503588036 K
mu = 0.18 Tc = 0.425181951443 K
mu = 0.20 Tc = 0.133454674518 K
a2F : 0.74s CPU 0.75s WALL ( 1 calls)
I read in some previous post that the logavg should be the logarithmic average phonon frequency, displayed in Ry. My next step was to try to convert it to Kelvin: logavg[K]=logavg[Ry]*157887=1103K. By entering this value into the McMillan formula, together with lambda=0.3208 and mu=0.1, it results in a crictical temperature of arround 1K, very different from the result of 5.9K.
So my main questions at this point are who are these two quantities displayed above the critical temperatures, and in which units are they being displayed.
Thanks in advance for any assistance
Fbio Costa