  The quantum Drude oscillator (QDO) is an efficient yet accurate
coarse-grained approach that has been widely used to model electronic and
optical response properties of atoms and molecules, as well as polarization and
dispersion interactions between them. Three effective parameters (frequency,
mass, charge) fully characterize the QDO Hamiltonian and are adjusted to
reproduce response properties. However, the soaring success of coupled QDOs for
many-atom systems remains fundamentally unexplained and the optimal mapping
between atoms/molecules and oscillators has not been established. Here, we
present an optimized parametrization (OQDO) where the parameters are fixed by
using only dipolar properties. For the periodic table of elements as well as
small molecules, our OQDO model accurately reproduces atomic (spatial)
polarization potentials and multipolar dispersion coefficients, elucidating the
high promise of the presented model in the development of next-generation
quantum-mechanical force fields for (bio)molecular simulations.

Chemical Physics