Classical molecular dynamics simulations are applied to isolated tetracene/(n-heptane)(n) clusters (n = 1-12). The spectroscopic shift of the aromatic molecule is calculated via evaluation of the dispersion terms in the perturbation expansion of the intermolecular interactions, using a multipole expansion of the interaction Hamiltonian. Stable structures, their energies and spectral shifts, optical lineshapes and vibrational modes are compared with two-color photo-ionisation spectra of such clusters in a molecular beam [Ben-Horin et al. Chem. Phys. Lett. 177, 153 (1991)]. Calculated shifts are in error by under 10% on average, enabling identification of most features of the experimental spectra. (C) 1997 American Institute of Physics. [S0021-9606(97)51242-6].