returns the total energy
function total_energy() result(etot_)
!! returns the total energy
!---------------------------------------------------------------------!
real(dp) :: etot_
!---------------------------------------------------------------------!
if (relative_energy_flag.eq.0) then
etot_ = energy
else if (relative_energy_flag.eq.1) then
etot_ = energy+internal_energies(initial_level)
endif
!---------------------------------------------------------------------!
end function total_energy