Vibrational spectrum of C70

✍ Scribed by Haibo Xia; Qing Jiang; Decheng Tian

• Publisher: Elsevier Science
• Year: 1992
• Tongue: English
• Weight: 241 KB
• Volume: 198
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(92)90056-s

✦ Synopsis

We report the vibrational density of states (VDOS) for the C7o molecule calculated using the recursion method. The Born potential is adopted for calculating the dynamic matrix. The results show that the peak positions of the VDOS for the C7o molecule are in reasonable qualitative agreement with those of Raman and infrared measurements.

The novel materials CN (N=60, 70, 84, ...), molecules and solids, have been prepared [ 1,2 ], arousing much scientific, and even public, interest. C6o and C7o have now been isolated by several different groups and their properties have been measured . Many theoretical studies have been reported on C6o and a few on C7o [20][28]. Though there have been some calculations of vibrational frequencies for the C7o molecule , as yet there have been no more sophisticated theoretical investigations on the vibrational spectrum for C7o. This Letter presents the first such calculations using the recursion method developed by Haydock, Heine, Kelly and Nex . We have obtained the vibrational density of states (VDOS) for the C7o molecule. The results show that the peak positions of the VDOS corresponding to the stronger vibrational modes for C7o are in reasonable qualitative agreement with those of Raman and infrared measurements.

The C7o molecule has a Dsh geometry, where a cylindrical belt of l 0 atoms has been added to C6o to yield a prolate spheroidal structure. These 10 added carbon atoms are all at the junction of three hexagons and thus most resemble the carbon in graphite (fig. ). Zhang et al. have shown the results of symmetry-unconstrained structure optimization simulations . They indicated that the average lengths for "double" and "single" bonds are 1.40 and 1.