Modified Gutzwiller theory of the metal-insulator transition: Application to heavy-fermion systems

The Gutzwiller and Hubbard approaches to the Hubbard Hamiltonian are each of a very different nature and lead to some qualitatively different results for certain quantities, for example, for the quasiparticle density of states as a function of the interaction divided by the bandwidth UW. The metal-to-insulator transition occurs for the Hubbard approach at UW 1 and for the Gutzwiller approach at UW=2. We suggest a simple modification of the Gutzwiller theory consisting of the use of a physically reasonable momentum distribution. We find the transition now occurring at UW 1 while the spin susceptibility and compressibility remain finite. Applications to heavy-fermion systems and normal He3 are discussed.