Systematic perturbative improvement of bound states on lattice.

•  

• All the higher-order Runge-Kutta corrections are interpreted as perturbations.

• Advantage: The "zero-order" discretization leaves the Hamiltonian tridiagonal, and

• one may apply my 1987 - 1991 perturbation prescription

• (recently re-discovered and using tridiagonal H_0).

•  

• Published in Phys. Lett. A 223 (1996) 411 - 416.