Pure translation instantaneous normal modes: Imaginary frequency contributions vanish at the glass transition in CS2

摘要: While the connection between imaginary frequency instantaneous normal modes (INM) and barrier crossing in liquids is well established, nondiffusive exist which must be removed theories of self-diffusion constant, D. It shown that molecular systems rotation primary source such modes. A new type pure translation (TR) INM introduced, describing center-of-mass motion. TR densities states, 〈ρTR(ω)〉, are obtained at several T for CS2. The Im-ω vanish glass transition their fraction, fuTR, has a dependence identical to Correspondingly, Re-ω density looses usual linear low-ω attains conventional ω2 behavior. proposed unmodified have negligible character naturally describe translational dynamics systems. Some general ideas given how properties, including importance modes, vary among different materials.