Coexistence of excited states in confined Ising systems

Using the density-matrix renormalization-group method we study the two-dime nsional Ising model in an infinite strip geometry with free-boundary condit ions. The renormalization scheme enables us to consider systems of width up to 300 (lattice spacings) and study the influence of the bulk magnetic fie ld on correlation function structure for all temperatures. Rom our numerica l results we have determined the crossover line for the correlation length related to the coexistence of the excited states. A detailed scaling study of this line is performed. Our numerical results support and further specif y previous conclusions reached by Abraham, Parry, and Upton based on the bu bble model of correlations.