General conditions for vanishing the current J^{z} for Dirac field on   boundaries of the domain between two planes
  In connection with the Casimir effect for a spinor field in presence of external magnetic field, of special interest are solutions of the Dirac equation in the domains restricted by two planes, which have vanishing the third projection of the conserved current J^{z} on two boundaries. General conditions for vanishing the current are formulated, they reduce to linear homogeneous algebraic system, for which solutions exist only when vanishing the determinant of the linear system, that is for the roots of a 4-th order algebraic equation with respect to the variable e^{2ik a}, where a is a half-distance between the planes, and k stands for the third projection of the Dirac particle momentum. All solutions of the equation have been found explicitly, each of them provides us in principle with a special possibility to get the quantization rules for parameter k; the most of produced expression for the roots can be solved with respect to parameter k only numerically. Generally, solutions e^{2ik a} depend on 4 arbitrary phase parameters which influence the appropriate wave functions with vanishing current: J^{z}(z=-z,+a)=0. 
O.V. Veko, V.M. Red'kov, A.I. Shelest, S.A. Yushchenko, A.M.   Ishkhanyan
quant-ph math-ph math.MP