LARGE PERMITTIVITY OF COMPUTER-SIMULATED LIQUID CYANOGEN

In order to explain the large permittivity of liquid cyanogen consisti ng of centrosymmetric molecules, a molecular dynamics simulation which includes all degrees of freedom of vibration, rotation, and translati on has been performed. The intramolecular potential energy is expresse d in terms of the internal coordinates with quadratic, cubic, and quar tic force constants. The intermolecular potential consists of an atom- atom pair potential with Coulombic and Buckingham terms. The simulatio n has given an adequate value of self-diffusion coefficient and a typi cal form of radial distribution function for the liquid state. The sim ulation has reproduced well the large value of the permittivity observ ed in experiments, suggesting that the value results from the extraord inarily large atomic polarization brought by the intramolecular bendin g motion in an antisymmetric mode. The simulation has also suggested t hat the nitrogen atoms collide with each other more frequently than wi th carbon atoms and the collision shifts the normal frequencies relate d to the N=C bond to higher frequency. The infrared and Raman spectra together with the real and imaginary parts of the refractive index hav e also been calculated.