Theoretical study on copper's energetics and magnetism in TiO2 polymorphs

Abstract

Abstract:Density functional theory calculations were employed to model the electronic structure and the magnetic interactions in copper doped anatase and rutile titanium dioxide in order to shed light on the potential of these systems as magnetic oxides using different density functional schemes. In both polymorphs copper dopant was found to be most stable in substitutional lattice positions. Ferromagnetism is predicted to be stable well above room temperature with long range interactions prevailing in the anatase phase while the rutile phase exhibits only short range superexchange interaction among nearest-neighbour Cu ions. Additionally, energetic evaluation of dopants in scattered and compact configurations reveals a dopant clustering tendency in anatase TiO 2 .

Graphene Young’s modulus: Molecular mechanics and DFT treatments

“…Specifically, this method is implemented for the study of systems which synthesizing them has a lot of difficulties. Since experimental studies in such systems, encumbered by incompatible results and non-equilibrium conditions these calculations are really necessary [47]. Also DFT has been admired for calculations in solid-state physics since the 1970s and the results obtained have agreed quite satisfactorily with experimental data [48][49][50][51] The first-principles DFT calculations were performed with a Local Combination of Atomic Orbital (LCAO) using the ab initio simulation code, Spanish Initiative Electronic Structure for Thousands of Atoms (SIESTA) [52,53].…”

“…With this theory, the properties of system can be determined by using their electron functions. Despite of popularity and versatility in computational physics and chemistry, there are still difficulties in describing intermolecular interactions, especially van der Waals forces [47]. Subsequently, DFT can be increasingly applicable for prediction of atomistic behavior of complex systems in the chemical and material science area.…”

“…Density functional theory (DFT) is one of the computational quantum mechanical modelling method which can be used in physics, chemistry and materials science in order to investigate their structure at an atomic scale [47]. With this theory, the properties of system can be determined by using their electron functions.…”

Roles of Cu concentration in the photocatalytic activities of Cu-doped TiO 2 from GGA+ U calculations

“…Some experimental and theoretical results show that TM atoms exhibit a weak trend of clustering. In addition, interstitial and oxygen sites are not preferable to accommodating Cu and other TMs [25]. Therefore, we concentrate on the atomic configurations with clustered Cu atoms.…”

“…However, the microscopic understanding of the enhanced photocatalytic activities of Cu-doped TiO 2 is limited, as compared to the investigations of other TM-doped TiO 2 . Almost no systematic theoretical exploration has been conducted on this material system [24][25][26]. In addition, from the available theoretical literature on TM-doped TiO 2 , we find that the great majority of works only consider how a fixed concentration of TM dopant reduces the band gaps of TiO 2 .…”