  Ultrafast laser excitation can induce fast increases of the electronic
subsystem temperature. The subsequent electronic evolutions in terms of band
structure and energy distribution can determine the change of several
thermodynamic properties, including one essential for energy deposition; the
electronic heat capacity. Using density functional calculations performed at
finite electronic temperatures, the electronic heat capacities dependent on
electronic temperatures are obtained for a series of metals, including free
electron like, transition and noble metals. The effect of exchange and
correlation functionals and the presence of semicore electrons on electronic
heat capacities are first evaluated and found to be negligible in most cases.
Then, we tested the validity of the free electron approaches, varying the
number of free electrons per atom. This shows that only simple metals can be
correctly fitted with these approaches. For transition metals, the presence of
localized d electrons produces a strong deviation toward high energies of the
electronic heat capacities, implying that more energy is needed to thermally
excite them, compared to free sp electrons. This is attributed to collective
excitation effects strengthened by a change of the electronic screening at high
temperature.
