Quantum melting on a lattice and a delocalization transition
E.V. Tsiper
and A.L. Efros
Department of Physics, University of Utah, Salt Lake City, UT 84112
We consider a two-dimensional gas of spinless fermions with Coulomb
and short-range interactions on a square lattice at T=0. Using the
exact-diagonalization technique we study finite clusters up to 16
particles at filling factors v =1/2 and 1/6. By increasing the
hopping amplitude we obtain the low-energy spectrum of the system in a
wide range from the classical Wigner crystal to an almost free gas of
fermions. Particular effort is made to study the mechanism of the
structural and insulator-metal transitions. We show that both
transitions are determined by the energy band of the defect with the
lowest energy in the Wigner crystal.