Theoretical Analysis of Structural, Energetic, Electronic, and Defect Properties of Li₂O

Abstract

The structural, energetic, and electronic properties of stoichiometric and defective Li(2)O were studied theoretically. The reliability of the Perdew-Wang method in the framework of density functional theory (DFT), and of two DFT/Hartree-Fock hybrid methods (PW1PW and B3LYP), was examined by comparison of calculated and available experimental data. Atom-centered orbitals and plane waves were used as basis functions for the crystalline orbitals. For both cases, the basis set dependence of calculated properties was investigated. With most of the methods, good agreement with the experimental Li(2)O lattice parameter and cohesive energy was obtained. In accordance with experiment, the analysis of electronic properties shows that Li(2)O is a wide gap insulator. Among the considered methods, the hybrid methods PW1PW and B3LYP give the best agreement with experiment for the band gap. The formation of an isolated cation vacancy defect and an F center in Li(2)O were studied. The effect of local relaxation on the calculated defect formation energies and the defect-induced changes of electronic properties were investigated and compared to available experimental results. The migration of a Li(+) ion in Li(2)O bulk was investigated. The activation energy for the migration of a Li(+) ion from its regular tetrahedral site to an adjacent cation vacancy was calculated, including the effect of local relaxation. The calculated activation barriers, 0.27-0.33 eV, are in excellent agreement with experiment.

Validation of potential models for Li2O in classical molecular dynamics simulation

“…In the present work, the diffusion barrier evaluated by DFT calculation was 0.24 eV in the same unit cell (Li 64 O 32 ) with Ref. [12]. Although the DFT calculation results in different techniques range from 0.24 to 0.33 eV, the values obtained in the four models could be significantly small.…”

“…As reference data, the experimental values [5][6][7][8][9][10][11] and the DFT calculation results in Table 1 Summary of the crystalline properties simulated in the four potential models Ref. [12] and the present study are listed, together with the reported results given by the AIM model [13]. The AIM model is one of the most reliable potential models.…”

The High-Temperature Transformation from 1T- to 3R-Li x TiS2 (x = 0.7, 0.9) as Observed in situ with Neutron Powder Diffraction

“…Since the quality of the wavefunction and therefore of the energies critically depends on the basis sets (BS), we employed three BS of increasing quality. A denotes the combination of (864-11G31d (Ti) [27], 7-11G1d (Li) [28], and 86-311G1d (S) [27]; in B, the sulfur BS was replaced by cc-pVTZ [29]; in C, sulfur and lithium BS are cc-pVTZ [30], and the titanium BS is a truncated def2-QZVPPD [31] without diffuse functions. In particular, the latter BS can be considered as close to the basis set limit.…”

Electronic Properties of Vanadium‐Doped TiO2

“…[47,48] PW1PW has been applied to calculations of bulk properties of MgO, NiO, CoO, [46] Li 2 B 4 O 7 , [49] B 2 O 3 , [50] and LiO 2 , [51] defect and electronic properties of TiO 2 , [33] LiBO 2 , [52] Li 2 B 4 O 7 , [53] and Li 2 O:B 2 O 3 nanocomposites, [54] electronic properties of Li 2 O-B 2 O 3 compounds, [55] and surface analysis of Li 2 O [56] and B 2 O 3 . [57] In these studies, good agreement between calculated and experimental properties was observed.…”