  We carry out state-of-the-art optimization of a nuclear energy density of
Skyrme type in the framework of the Hartree-Fock-Bogoliubov (HFB) theory. The
particle-hole and particle-particle channels are optimized simultaneously, and
the experimental data set includes both spherical and deformed nuclei. The new
model-based, derivative-free optimization algorithm used in this work has been
found to be significantly better than standard optimization methods in terms of
reliability, speed, accuracy, and precision. The resulting parameter set
UNEDFpre results in good agreement with experimental masses, radii, and
deformations and seems to be free of finite-size instabilities. An estimate of
the reliability of the obtained parameterization is given, based on standard
statistical methods. We discuss new physics insights offered by the advanced
covariance analysis.
