PARTICLE-HOLE ASYMMETRY IN THE 2-IMPURITY KONDO MODEL

A modified numerical renormalization-group procedure, preserving the p article-hole asymmetry of the two-impurity Kondo model, calculates the susceptibility, over 13 decades of temperature, and low-temperature s pecific heat. For large ferromagnetic RKKY couplings, a two-stage Kond o effect screens the triplet-correlated moments. For large antiferroma gnetic couplings, the impurities develop singlet correlations and cont ribute Van Vleck terms to the low-temperature properties. For vanishin g particle-hole asymmetry, previously found critical behavior emerges at low temperatures.