Purpose The purpose of this paper is to analyze various properties of anatase titanium dioxide (TiO2) nanoparticles. Further, it proposes to implement Linear Combinations of Atomic Orbitals (LCAO) basis set under the framework of density functional theory and outline how LCAO is able to provide improved results in terms of various mechanical properties rather than plane wave and other theoretical results. Design/methodology/approach This paper provides an exploratory study on anatase TiO2 by implementing OLCAO–DFT–LDA–LBFGS–EOS–PZ algorithms to find out various ground-level properties. The data so obtained are complemented by various analysis using mathematical expressions, description of internal processes occurred and comparison to others’ analytical results. Findings The paper provides some empirical insights on how mechanical properties of anatase TiO2 improved by implementing LCAO methodology. From the analysis of electronic properties, it is seen that the anatase TiO2 supports the inter band indirect transition from O-2p in valence region to Ti-3d in the conduction region. Research limitations/implications Most of the electronic properties are underestimated because a single exchange-correlation potential is not continuous across the gap. This gap can be enhanced by implementing Green’s function in place of DFT and the other way is to implement self-interaction correction. Practical implications The use of anatase TiO2 is primarily used for catalytic applications. This is also used to enhance the quality of paper in the paper industry. Additionally, this is used as a prime ingredient in cosmetic industry. Originality/value This paper fulfills an identified need to study how LCAO, another basis set, plays an important role in improving material properties.

The impact of high-k dielectric pocket (DP) on the ambipolar conduction of tunnel field-effect transistors (TFETs) is demonstrated using two-dimensional Technology Computer Aided Design (TCAD) simulations. In the proposed structure of TFETs, an optimised portion of the upper drain region is replaced with a high-k DP at the channel-drain interface. It is demonstrated that due to the enhancement of the depleted drain region under DP, the minimum tunnelling width at channel-drain interface increases, and attains a maximum value for an optimum length and thickness of DP. Eventually, this increment in the minimum tunnelling width leads to a significant reduction in ambipolar conduction in TFETs. Furthermore, it is shown that performance parameters including the ON-state current, subthreshold swing and output characteristics are not affected by the presence of the proposed DP. Even, the gate-to-drain capacitance is reduced with the inclusion of DP at the channel-drain interface, thus leading to an improved cutoff frequency of TFETs. Moreover, it is also demonstrated that only a 10 nm of gate-on-drain overlapping along with this DP is capable of eliminating the ambipolarity completely for even a higher gate voltage of −0.8 V.

We present an analysis of structural, electronic, and mechanical properties of cubic titanium dioxide (TiO 2 ) using an all electron orthogonalzed linear combinations of atomic orbitals (OLCAO) basis set under the framework of density functional theory (DFT). The structural property, especially the lattice constant a, and the electronic properties such as the band diagram and density of states (DOS) are studied and analyzed. The mechanical properties such as bulk moduli, shear moduli, Young's Moduli, and Poison's ratio are also investigated thoroughly. The calculations are carried out on shear moduli and anisotropy factor for cubic TiO 2 . The Vickers hardness is also tested for fluorite and pyrite cubic-structured TiO 2 . Furthermore, the results are compared with the previous theoretical and experimental results. It is found that DFTbased simulation produces results which are approximation to experimental results, whereas the calculated elastic constants are better than the previous theoretical and experimental values.

In this paper, a Self-consistent Orthogonalized linear combination of atomic orbitals (OLCAO) technique with a generalized gradient approximation such as Perdew-Burke-Ernzerhof Solid (GGA-PBE SOL) has been used to scrutinize the structural, optical, electronic and mechanical properties of normal pressure phase (Anatase and Rutile) and high pressure phase i.e., cubic (Fluorite and Pyrite) TiO 2 . Electronic and optical properties of normal pressure phases of TiO 2 are also investigated using (Meta) MGGA-Tran and Blaha (TB09) and obtained results are a close approximation of experimental data. It is seen that the virtually synthesized structural parameter for cubic and tetragonal phases of TiO 2 are consistent with experimental and theoretical data. From the effective mass of charge carriers (m * ), it can be observed that pyrite TiO 2 is having lower effective mass than the fluorite and hence shows higher photocatalytic activity than fluorite. Furthermore, it is seen that fluorite is more dense than anatase, rutile and pyrite TiO 2 . From the theoretical calculations on the optical properties, it can be concluded that optical absorption occursin the near UV region for high and normal pressue phases of TiO 2 . Again from the reflectivity characteristics R(ω), it can be concluded that TiO 2 can be used as a coating material. Elastic constants, elastic compliance constants, mechanical properties are obtained for anatase, rutile, fluorite and pyrite TiO 2 . A comparison of the results with previously reported theoretical and experimental data shows that the calculated properties are in better agreement with the previously reported experimental and theoretical results.

In this paper, a novel structure of cylindrical GAA-TFETs with high-k dielectric pocket is proposed to improve the analog and highfrequency performances. We have discussed the device physics of proposed structure in details with the help of 3-D TCAD simulation. Since, an optimum part of the drain region is replaced with a high-k dielectric material (HfO 2 ), oxide-semiconductor interface formed between channel and dielectric pocket increases the tunneling width at channel-drain junction. Further, this increment in tunneling width caused by depleted drain region under dielectric pocket eventually reduces the ambipolar conduction and OFF-current without deteriorating ON-current and subthreshold slope. It is observed that device performances are improved with increasing pocket length and thickness up to a value of 30-nm and 4-nm respectively; beyond which either device performances are degraded or dependences become poor. The advantages of using a high-k dielectric material over low-k are demonstrated in terms of reduction in ambipolar conduction, and immunity against degradation in current switching ratio during device scaling. Additionally, the impact of high-k dielectric pocket on high-frequency performances is demonstrated. Unlike tunnel FETs with dielectric spacer, it is observed that drain-to-gate capacitance is reduced for our proposed device which further leads to improvement in cutoff frequency.