Anomalous non-additive dispersion interactions in systems of three one-dimensional wires

The non-additive dispersion contribution to the binding energy of three one-dimensional (1D) wires is investigated using wires modelled by (i) chains of hydrogen atoms and (ii) homogeneous electron gases. We demonstrate that the non-additive dispersion contribution to the binding energy is significantly enhanced compared with that expected from Axilrod-Teller-Muto-type triple-dipole summations and follows a different power-law decay with separation. The triwire non-additive dispersion for 1D electron gases scales according to the power law d^-β, where d is the wire separation, with exponents β\(r_s\) smaller than 3 and slightly increasing with r_s from 2.4 at r_s = 1 to 2.9 at r_s=10, where r_s is the density parameter of the 1D electron gas. This is in good agreement with the exponent β=3 suggested by the leading-order charge-flow contribution to the triwire non-additivity, and is a significantly slower decay than the sim d^-7 behaviour that would be expected from triple-dipole summations.