We introduce a new type of boundary conditions, smooth boundary conditions, for numerical studies of quantum lattice systems. In a number of circumstances, these boundary conditions have substantially smaller finite-size effects than periodic or open boundary conditions. They can be applied to nearly any short-ranged Hamiltonian system in any dimensionality and within almost any type of numerical approach.

• Received 1 September 1993

DOI:https://doi.org/10.1103/PhysRevLett.71.4283