Environmental problems associated with water pollution caused by organic dyes have raised serious concerns. In this context, photocatalytic processes proven to be promising and environmentally friendly methods for purification utilising abundant solar energy. study, a SrTiO

The total energy and geometry of nanoclusters are calculated using evolutionary structure searching density functional theory. calculation shows that the arrangement Si atoms is close to diamond crystal only in cluster , while others it unique for each composition. We found ensemble clusters remains uniform after passivation if hydrogen concentration corresponds one stable compositions???, or . Passivation by an arbitrary amount converts into a mixture having nearest compositions. In...

Oxidation of silicon nanoclusters depending on the temperature and oxygen pressure is explored from first principles using evolutionary algorithm, structural thermodynamic analysis. From our calculations 90 SinOm clusters we found that under normal conditions oxidation does not stop at stoichiometric SiO2 composition, as it in bulk silicon, but goes further placing extra atoms cluster surface. These are responsible for light emission, relevant to reactive species many them magnetic. We argue...

A brief review is given on the studies of ferroelectricity in perovskites. Early phenomenological theories displacement-type ferroelectrics are considered. Two markedly different approaches based density-functional theory described. In one approach, electron density crystal determined as a sum Bloch functions. other, it constructed superposition densities individual ions. The latter approach gives microscopic justification for old theories. We show that some phenomena perovskites, which...

Numerical calculations of surface and volume plasma excitations in silicon silicon-hydrogen nanoclusters the range Si$_{10}$-Si$_{60}$ Si$_3$H$_8$-Si$_{39}$H$_{40}$ are performed. Some nanocluster structures were obtained using evolutionary algorithm, others taken from database. The GW method was used to calculate response function self-energy under study. applied shows results consistent with experiment (except plasmaron artifacts) sufficient sensitivity allowing investigate effect cluster...

The atomic structure and electronic spectrum of silicon nanoclusters (Si-ncs) Si7, Si10,Si10H16 Si10H20 are calculated using the evolutionary algorithm with total energy computed within density functional theory generalized gradient approximation (DFT-GGA). When analysing low-energy structures, we pay significant attention to their symmetry interatomic bond geometry. candidate structures arising in process convergence also considered classified by topology grouping near local minima....

The first-principle prediction of nanocluster stable structure is often hampered by the existence many isomer configurations with energies close to ground state. This fact attaches additional importance many-electron effects going beyond density functional theory (DFT), because their contributions may change a subtle energy order competitive structures. To analyze this problem, we consider, as an example, energetics silicon nanoclusters passivated hydrogen Si$_{10}$H$_{2n}$ $0\le n\le 11$,...

We investigate the structural and thermodynamical properties of small silicon clusters. Using graph theory applied to previously obtained structures Si10H2m clusters we trace connection between geometry passivation degree. The existing data on these Si10O4n here using evolutionary calculations allowed analyze features in hydrogen atmosphere oxygen atmosphere. have shown basic differences clusters, passivated by oxide

Formation of surface plasmon modes in sodium nanoclusters containing 20-300 atoms was studied using the GW method. It is shown that small Na nanoparticles up to 2 nm size, loss function $Im[\epsilon^{-1}]$ dominated by a single peak corresponding localized resonance (LSPR). For particles and more, polariton (SPP) oscillations begins form, as well volume (VP) excitations. Considering above, linear size particle range 0.7-3.7 can be estimated lower limit for metal nanodevices operating with...

The total energy, geometry and electronic spectra of nanoclusters \shm{} ($m=0\ldots11$) are calculated using the evolutionary algorithm density functional theory (DFT). It is shown, that features electron spectrum, namely HOMO-LUMO gap valence band width, correlate with cluster stability. becomes wider as number hydrogen atoms increases whereas width gets lower. widening indicates increasing stability which consistent existing data on reaction energy.

A loss of metallic properties in fcc calcium under high pressure is studied ab initio using the density functional theory (DFT) and GW approximation. It found that a more correct description many-electron effects given by method does not provide significant changes behavior electronic spectrum comparison with DFT approach. We note obtained width (pseudo)gap highly sensitive to k-point sampling used for states calculation. The analysis calcium's band structure at p ~ 20 GPa shows crossing...

It is well known that collective electronic excitations in fullerene C$_{60}$ are manifested as Mie plasmons, and graphene (the limiting case of an infinitely large fullerene) plasmon-polariton type. How the properties plasmons change fullerenes with intermediate sizes poorly understood. This problem considered current paper framework GW approximation on example C$_{60}$, C$_{240}$ C$_{540}$. The calculations show a high-frequency resonance begins to form C$_{240}$, C$_{540}$ intensity this...

The work is devoted to the formation energy calculations of intrinsic defects in silicon based on GW method and Galitskii-Migdal formula. two methods for calculating electronic response function are applied. first one uses direct integration over frequency determine function. diagonal form spectral only assumption within RPA framework, but supercell very time-consuming. Therefore, we propose which calculated plasmon pole approximation, contribution exchange-correlation taken with a certain...

The work is devoted to the formation energy calculations of intrinsic defects in silicon based on $GW$ method and Galitskii-Migdal formula. Two methods for calculating electronic response function are applied. first one uses direct integration over frequency determine function. diagonal form spectral only assumption within random phase approximation (RPA) framework, but supercell very time consuming. Therefore, we propose which calculated plasmon pole approximation, contribution...