  We study the zero-temperature quantum phase transition between liquid and hcp
solid helium-4. We use the variational method with a simple yet
exchange-symmetric and fully explicit wavefunction. It is found that the
optimized wavefunction undergoes spontaneous symmetry breaking and describes
the quantum solidification of helium at 22 atm. The explicit form of the
wavefunction allows to consider various contributions to the phase transition.
We find that the employed wavefunction is an excellent candidate for describing
both a first-order quantum phase transition and the ground state of a Bose
solid.
