On the structure and normal modes of hydrogenated Ti-fullerene compounds

Abstract

When titanium covers a C 60 core, the metal atoms may suppress the fullerene's capacity of storing hydrogen, depending on the number of Ti atoms covering the C 60 framework, the Ti-C binding energy, and diffusion barriers. In this article, we study the structural and vibrational properties of the C 60 TiH n (n = 2, 4, 6, and 8) and C 60 Ti 6 H 48 compounds. The IR spectra of C 60 TiH n compounds have a maximum attributable to the Ti-H stretching mode, which shifts to lower values in the structures with n = 4, 8, while their Raman spectra show two peaks corresponding to the stretching modes of H 2 molecules at apical and azimuthal positions. On the other hand, the IR spectrum of C 60 Ti 6 H 48 shows an intense peak due to the Ti-H in-phase stretching mode, while its Raman spectrum has a maximum attributed to the pentagonal pinch of the C 60 core. Finally, we have found that the presence of one apical H 2 molecule enhances the pentagonal pinch mode, becoming the maximum in the Raman spectrum.

Interplay of Bias-Driven Charging and the Vibrational Stark Effect in Molecular Junctions

“…(Importantly, the calculated vibrational spectrum for gas-phase PCBM is in good agreement with prior work. For example, for prominent modes such as the primary C−H 2 /C−O peak and CO stretch found at 1163 and 1745 cm −1 , respectively, our calculations agree well with previous calculations 34 (1152 and 1732 cm −1 ) and experiments 35,36 (1187 and 1738, 1740 cm −1 ). For the above model parameters, the calculated bias-induced vibrational shifts for PCBM, including both field and charging effects, show linear components of up to ∼2 cm −1 /V and quadratic elements of up to ∼7 cm −1 /V 2 in magnitude at maximum field (1.4 V/nm).…”

“…Therefore the results shown here were all computed with standard basis sets -see the SI for more details † Importantly, the calculated vibrational spectrum for gas-phase PCBM is in good agreement with prior work. For example, for prominent modes such as the primary C-H 2 /C-O peak and C=O stretch found at 1163 cm -1 and 1745 cm -1 , respectively, our calculations agree well with previous calculations 34 (1152 cm -1 and 1732 cm -1 ) and experiments 35,36 (1187 and 1738, 1740 cm -1 ).] To lowest order, the linear term in the vibrational Stark effect is known to originate with the second derivative of the induced dipole moment with mode displacement 37 , which will only be nonzero for IR active (or polar) vibrational modes.…”

New insight into the structure of the C60Sc20 cluster: bonding, vibrational and optical properties

“…Following this line of thought, there was a report devoted to C 60 Ti 6 H 48 that features a structure in which the transition metal atoms are far enough away from each other that their clustering is avoided. 14 So it seems obvious that in the pursuit of adding a maximum number of transition metals to the C 60 framework, those studies might conduce to the computational discovery of the volleyballene structure.…”

Hydrogen Storage on Volleyballene: Prediction of the Sc20C60H70 Cluster

“…In 2016, the structure of volleyballene (hereafter named as V ball) was proposed by Wang et al and Tlahuice-Flores carried out vibrational and absorption spectra calculations to help into its identification. Volleyballene structure is comprised by scandium atoms that are incorporated into its framework, and therefore its hydrogenation capacity is maintained due to the lack of clustering efects. , Noteworthy is that the formula of volleyballene (Sc 20 C 60 ) resembles that of the well-known C 80 fullerene but the displayed bonding closely resembled one of the early hypotheses of Alvarez et al. in 1991 for the LaC 82 and La 2 C 80 series, where two carbon atoms are substituted by that of one transition metal …”

“…Volleyballene structure is comprised by scandium atoms that are incorporated into its framework, and therefore its hydrogenation capacity is maintained due to the lack of clustering efects. 9,10 Noteworthy is that the formula of volleyballene (Sc 20 C 60 ) resembles that of the well-known C 80 fullerene but the displayed bonding closely resembled one of the early hypotheses of Alvarez et al in 1991 for the LaC 82 and La 2 C 80 series, 11 where two carbon atoms are substituted by that of one transition metal. 12 The importance of this study is based on the necessity of clean electricity that can be provided by hydrogen (fuel cells); hence, the search of a new material able to store hydrogen represents an opportunity area.…”