i met some difficulties in realizing TTM-MD with AtC package. i added domain source as a laser source to electron temperature field and got a significant higher temperature value than predicted.
and i found that it is the unchanged electron heat capacity that lead to this disaster.
here are the details:
i was trying to use AtC pack to study the laser ablation of 30nm gold foil.
i considered the electron heat capacity(C_e) with dependence of elertron temperature(T_e) and set the ‘capacity’ = 71 J/(m^3 K^2) with ‘linear’ label in the material file. the units was translated into the metal units in AtC (energy defined by length, mass and time)
according to the free electron gas model, we have C_e = gamma * T_e. based on this, we can calculate the temperature change in given energy deposition. i used ‘fix source’ and the energy deposition rate is 1.3*10^22 W/m^3, both electron and atom temperature is initialized to 300K. therefore, not considering the energy exchange between phonon and electron, the predicted electron_temperature would be about 8,500K. however the simulation result is about 122,000K, which is significantly higher than theorectical one.
After a few days of troubleshooting, i found that, if i chose the value C_e = 300K * gamma as constant electron heat capacity, the calculated final T_e value would be about 122,000K ,which is similar to the simulation result
that is to say, although i set the C_e to be ‘linear’(proportional to T_e), it did not update to a new value over the simualtion !
that confused me.
so my question is , how can i fix this problem that C_e does not update over time? is that i missed some 'command’s? or it is the mistake of the package?
thanks in advance