Self-adjoint Dirac type Hamiltonians in one space dimension with a mass   jump
  Physical self-adjoint extensions and their spectra of the one-dimensional Dirac type Hamiltonian operator in which both the mass and velocity are constant except for a finite jump at one point of the real axis are correctly found. Different boundary conditions on envelope wave functions are studied, and the limiting case of equal masses (with no mass jump) is reviewed. Transport across one-dimensional heterostructures described by the Dirac equation is considered. 
L. A. Gonz\'alez-D\'iaz, Alberto A. D\'iaz, S. D\'iaz-Sol\'orzano and   J. R. Darias
quant-ph math-ph math.MP