Two-body problem in a many-particle system

Abstract
The energy and wave functions of two-particle states in a dense plasma are essentially influenced by the surrounding medium. However, the two-particle bound-state energies may remain unshifted over a large density interval. Two simple examples are given to demonstrate the compensation of many-particle effects such as self-energy and effective two-particle potentials in hydrogen plasmas. Neglecting self-energy and Pauli blocking, we obtain energy values that follow from numerical solutions of the Schrödinger equation with a Debye potential.