Make ZeroTemperature an Approximation #13
Description
Description
There is no reason that IdealElectronSystem is parameterized with the temperature mode. Actually, it is inconvenient, because the approximations do not work for both finite and zero temperature.
It would be more convenient if the ZeroTemperature mode became an approximation (like ZeroTemperatureApproximation), because with NonDegenerated we already have an approximation which, more or less, looks at certain temperature ranges.