Hi Pedram, the two "temperatures" are totally decoupled and stay in no relation one to the other.
The ElectronicTemperature a priori has nothing to do with molecular dynamics; its effect is on electronic structure iterations, irrespectively of whether the calculation is static or dynamic. As explained in the manual, it controls the width of the Fermi step function. Think of it as merely an artificial smearing parameter, to smoothen the electronic structure iterations. It is particularly useful if you have a metal or narrow band gap, where there are many levels close to HOMO - LUMO. Note that the exact value of total energy depends on this parameter quite a lot. You may wish to start calculation with its value of say 300 - 600 K but then take care to reduce it to a small enough value that the total energy does not vary with it any more. The temperature definition(s) in the MD part controls the thermostat and hence the "classical" behaviour of atoms, without directly affecting the electrons. Best regards Andrei Postnikov > Hi, > > I have problem with temperatures in MD Anneal in Si.fdf that is present in > "tests" directory in siesta code. (I have enclosed the .fdf) > > There, I can see the electronic temperature is 300K and two other > parameters as: > > MD.InitialTemperature 100 K > MD.TargetTemperature 600 K > > To my understanding, the electronic temperature comes from the fermi-dirac > distribution and deals with the valence "electrons" but MD temperatures > come from Maxwell-Boltzmann distribution for "atoms" and should consider > the role of the nuclei as well, if I am not mistaken. > > What is exactly the point of mentioning the temperature in two different > distributions in one MD simulation? > > Thanks, > Pedram >
