New orderings for effective mass Hamiltonians and associated   wavefunction matching conditions at abrupt heterojunctions
  We show that for a given setting of the Von Roos ambiguity parameters, it is not required that the Morrow and Brownstein condition be satisfied to achieve physically acceptable transport properties at abrupt heterojunctions. We have derived two such settings and corresponding envelope function matching conditions. 
Mercel Vubangsi (MMLS), Martin Tchoffo (MMLS), Lukong Cornelius Fai   (MMLS)
quant-ph