COLLECTIVE EXCITATIONS IN LIQUID DEUTERIUM - NEUTRON-SCATTERING AND CORRELATED-DENSITY-MATRIX RESULTS

The collective dynamics of liquid deuterium is studied by means of ine lastic neutron scattering (INS) at 20.14 K and under 2 bars of applied pressure using two different incident energies. The low-incident-ener gy (high-energy-resolution) spectra are studied in detail by means of a time-of-flight (TOF) technique, whereas the finite-frequency respons e is investigated using a higher incident energy on a triple-axis spec trometer (TAS). The main finding of our work is the observation by the latter experimental technique of well-defined collective excitations up to a momentum transfer of 3.8 angstrom-1. Comparisons are establish ed with the dispersive behavior observed in other liquid systems as we ll as with the predictions from recent correlated-density-matrix calcu lations.