[en] This paper presents ab initio self-consistent field crystal orbital calculations on the structures, stabilities, elastic and electronic properties of the double-wall nanotubes made of SiO₂ nanotubes encapsulated inside zigzag carbon nanotubes based on density functional theory. It is found that formation of the combined systems is energetically favorable when the nearest distance between the two constituents is in the area of the van der Waals effect. The obtained band structures show that all the combined systems are semiconductors with nonzero energy gaps. Based on the deformation potential theory and effective mass approximation, the mobilities of charge carriers are calculated to be in the range of 10²-10⁴ cm ² V ^-1 s ^-1, the same order of magnitude as those of the corresponding zigzag carbon nanotubes. The Young’s moduli are also calculated for the combined systems. (paper)

[en] The structure stabilities and electronic properties are investigated by using ab initio self-consistent-field crystal orbital method based on density functional theory for the one-dimensional (1D) double-wall nanotubes made of n-gon SiO_2 nanotubes encapsulated inside zigzag carbon nanotubes. It is found that formation of the combined systems is energetically favorable when the distance between the two constituents is around the Van der Waals scope. The obtained band structures show that all the combined systems are semiconductors with nonzero energy gaps. The frontier energy bands (the highest occupied band and the lowest unoccupied band) of double-wall nanotubes are mainly derived from the corresponding carbon nanotubes. The mobilities of charge carriers are calculated to be within the range of 10"2–10"4 cm"2 V"−"1 s"−"1 for the hybrid double-wall nanotubes. Young’s moduli are also calculated for the combined systems. For the comparison, geometrical and electronic properties of n-gon SiO_2 nanotubes are also calculated and discussed. - Graphical abstract: Structures and band structures of the optimum 1D Double walls nanotubes. The optimized structures are 3-gon SiO2@(15,0), 5-gon SiO2@(17,0), 6-gon SiO2@(18,0) and 7-gon SiO2@(19,0). - Highlights: • The structure and electronic properties of the 1D n-gon SiO_2@(m,0)s are studied using SCF-CO method. • The encapsulation of 1D n-gon SiO_2 tubes inside zigzag carbon nanotubes can be energetically favorable. • The 1D n-gon SiO_2@(m,0)s are all semiconductors. • The mobility of charge carriers and Young’s moduli are calculated

[en] The structure–property relationship of the nanopeapods—one dimensional (1D) C₆₀O polymer encapsulated in single-walled carbon nanotubes (SWCNTs)—is studied by means of the self-consistent field crystal orbital method. The calculations show that the nearest distance between the two constituents is within Van der Waals interaction scope in the most stable two peapods. The SWCNT sizes affect not only the stability but also the electronic structures of the peapods. The peapods with larger tube diameters keep the semiconductive and metallic properties of the corresponding pristine SWCNTs. These combination systems are stiffer than the corresponding SWCNTs due to larger Young's moduli. The magnitude order of the calculated mobility of charge carriers is in the range of 10²–10⁵ cm² V⁻¹ s⁻¹ for the peapods, indicating that the combined systems may be good high-mobility electronic materials. - Graphical abstract: Formation of the novel peapod—1D C₆₀O polymer encapsulated inside single-walled carbon nanotube. Highlights: ► Several novel peapods encapsulating one dimensional C₆₀O polymers are constructed. ► Interwall distance of the two most stable peapods is in the Van der Waals scope. ► All peapods studied are stiffer than the corresponding SWCNTs. ► These peapods have high mobilies—in the order of 10²–10⁵ cm² V⁻¹ s⁻¹.

[en] The four new modified nucleobases (NBs), 5-mC, 5-hmC, 5-fC and 5-caC, besides the regular adenine, thymine, cytosine, guanine and uracil, are important in expression and regulation of genetic information. These four new major NBs are all derived from base cytosine by adding various functional groups, and their identification from the regular ones are much desired currently. However, the four new major NBs interacted with graphene on its surface have not been well considered, though a number of studies of regular NBs adsorbed on low-dimensional carbon materials are available to identify different NBs. This work reveals the interaction between the four new major NBs and graphene nanoflake substrate by using first-principle calculations based on density functional theory. The structure, energy and non-covalent interaction of the graphene/NBs complex are calculated and explored in details. The energy decomposition analysis, reduced density gradient, charge transfer and projected density of states are also performed to investigate the nature of the interaction between NBs and graphene nanoflake. Electrostatic and orbital interaction are found to be important to stabilize the interaction between NBs and graphene nanoflake, though orbital interaction is less significant. It is very noticed that the proportion of dispersion interaction could be more than half of the sum attractive contributions. Thus, dispersion interaction is the most dominating factor in stabilizing graphene/NBs complexes. The results of reduced density gradient further confirm that the interaction between the graphene nanoflake and NBs is mainly the van der Waals type. Besides, much attention is paid to the interaction differences between the four new major NBs and the pristine cytosine, and the impact of the introduced functional groups of the four new major NBs on the structure, energy and interaction is also discussed.