Phonon dispersion in poly(dimethylsilane) |
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Authors: | Ruchi Agarwal Vishwambhar Dayal Gupta |
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Affiliation: | Physics Department, Lucknow University, University Road, Lucknow 226007, Uttar Pradesh, India |
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Abstract: | In the present communication we report normal modes and their dispersion in polydimethylsilane (PDMS) [-Si(CH3)2-]n using Urey-Bradley force field, which in addition to valence force field accounts for the non-bonded interactions in the gem and cis configurations and tension terms. The partially deuterated PDMS (PDMS-d3), i.e., (SiCH3CD3)n and fully deuterated PDMS (PDMS-d6), i.e., (SiCD3CD3)n are also studied to check the assignments and validity of the force field. Dispersion curves show two interesting features: (1) a divergence of dispersion curves following repulsion of species belonging to the same symmetry; (2) crossing between the two modes. In addition, heat capacity as a function of temperature via density-of-states is evaluated and some of the modes left unassigned by the earlier workers have been assigned. |
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Keywords: | Poly(dimethylsilane) Phonon dispersion Density-of states Heat capacity Infrared spectra Raman spectra |
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