Accurate quantum calculations of translation-rotation eigenstates in electric-dipole-coupled H₂O@C₆₀ assemblies

We present methodology for variational calculation of the 6n-dimensional translation-rotation (TR) eigenstates of assemblies of n H₂O@C₆₀ moieties coupled by dipole-dipole interactions. We show that the TR Hamiltonian matrix for any n can be constructed from dipole-dipole matrix elements computed for n=2. We present results for linear H₂O@C₆₀ assemblies. Two classes of eigenstates are revealed. One class comprises excitations of the 1₁₁ rotational level of H₂O. The lowest-energy 1₁₁-derived eigenstate for each assembly exhibits significant dipole ordering and shifts down in energy with the assembly size.