Fix energy scale for chemical potential root finding.
Fix energy scale for chemical potential root finding.

For high density uegs in larger basis sets (at higher temperatures) we
can run into numerical precision issues when ensuring convergence of the
chemical potential. Using reduced units, with the energy scale set by
the Fermi energy, sets a more sensible threshold.

hande-qmc/hande,hande-qmc/hande,hande-qmc/hande,ruthfranklin/hande,hande-qmc/hande,hande-qmc/hande