Hasan Abu Kassim, Norhasliza Yusof, Vr Devi and Keshav N Shrivastava
Keywords: SiSe glass, raman, Ab initio, vibrations.
Abstract: The vibrational frequencies of several clusters of atoms, Si4Se, CS-Si4Se,SiSe4, CS-SiSe4, SiSe3, Si3Se, Si2Se3, Si3Se2, L-Si4Se5, and ES-Si2Se6. In the pyramidal configuration Si4Se shows nine different phonon modes at 233, 398, 416, 464, 478, 501, 601, 631 and 686 cm-1 . When atoms are rearranged as Si2SeSi2 stable configuration has only one low lying mode at 56 cm-1. Similarly, planar ion-exchange cluster, corner sharing (CS), CS-SiSe4 shows only two vibrational modes at 75 and 96 cm-1. The pyramidal SiSe4 has the expected vibrations of symmetries A1, A2 and E. The pyramidal configurations have the normal symmetries which break upon rearranging atoms. By means of ab initio predictions of vibrational frequencies of clusters of atoms, CSSi4Se, linear chain mode (CM), CM-Si4Se5, Si2Se3, Si3Se2, Si4Se and comparison with those found experimentally from the Raman spectra in SiSe2 glass, we are able to identify that these clusters are present in the glass.
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