Platinum(II) and phosphine MM3 force field parameters are derived from fits to the ground state potential energy surface at the level of Kohn-Sham density functional theory with employment of the B3LYP exchange-correlation functional. The parametrization includes bond stretch, angle bend, and torsional parameters for a planar platinum(II) center with phosphine and ethynyl ligands. The force field is used to study the dynamics of a fifth-generation dendrimer-coated platinum(II)organic compound in tetrahydrofurane solution at room temperature, and, based on a selection of conformations from the molecular dynamics simulation, the averaged linear absorption spectrum is determined with use of the CAM-B3LYP functional. The main absorption peak in the theoretical absorption spectrum is found at a transition wavelength of 325 nm with a full-width at half-maximum of 26 nm due to conformational broadening.