Results 211 to 220 of about 225,991 (262)

Theoretical studies of off-centre Sc3+ impurities in CeO2

Journal of Physics and Chemistry of Solids, 1989
Abstract We report results of a computer simulation study of the structure of an isolated Sc 3+ substitutional ion in doped ceria. It is shown that there is a stable low symmetry dipolar structure for the Sc impurity, in which the surrounding cage of eight oxygen ions is distorted more so than the Sc ion itself.
A N Cormack, A S Nowick, C R A Catlow
exaly   +2 more sources

Ab initio theoretical study of three-centre bonding on the basis of bond index

Computational and Theoretical Chemistry, 2000
Abstract Various methods of derivation of a multi-centre bond index and its physical significance are briefly discussed. The usefulness of the bond index model for the study of three-centre (3c) bonding is illustrated by taking a number of examples chosen from earlier calculations.
A B Sannigrahi, T Kar
exaly   +2 more sources

A theoretical study of H-centre migration in alkali halide crystals KCl and NaCl

Philosophical Magazine A: Physics of Condensed Matter, Structure, Defects and Mechanical Properties, 1993
Abstract Two different theoretical techniques, ab initio Hartree-Fock cluster calculations, and that of atom-atom potentials, as implemented in the CASCADE code, are employed for simulating on-site and saddle-point positions of primary Frenkel defects (H centres) in NaCl and KCl crystals. In both types of calculations H centres are found to be oriented
E A Kotomin, P W M Jacobs
exaly   +2 more sources

A theoretical study of F centres in BaClF and SrClF

Solid State Communications, 1976
Abstract We present point-ion calculations of the electronic structure of F centres in BaClF and SrClF. The relative positions of the singlet and doublet absorption bands of the F centres at F − and Cl − sites suggest a new assignment of the bands to the F centre sites.
S. Lefrant, A.H. Harker
openaire   +1 more source

Theoretical study of the distortion around F centres and the interaction between F centres in NaCl

Physica B+C, 1978
Abstract The distortions around an F centre are studied using an elastic strength for the defect as given by the lattice statics theory of Kanzaki. The defect is simulated by imposing different types of forces on the neighbours, and the resultant displacements calculated.
Y.V.G.S. Murti, V. Usha
openaire   +1 more source

A theoretical study of three-centre M–H–C interactions

J. Chem. Soc., Dalton Trans., 1985
The results of extended-Huckel calculations on some complexes of general formula [M(cycloalkenyl)L3]n, which are known to possess agostic M–H–C interactions, are presented. The effects of changes in M and L are investigated and compared with experimental observations.
Noel J. Fitzpatrick, Michael A. McGinn
openaire   +1 more source

Theoretical study of Ce2+ cubic centres in alkaline earth fluoride crystals

Radiation Measurements, 2016
Abstract In this paper we present theoretical study of Ce 2+ impurity centres in alkaline earth fluoride crystals (CaF 2 , SrF 2 ). Only cubic configurations of centres were considered. Electronic levels and related properties were studied using CASSCF/CASPT2 approach within embedded-cluster formalism including scalar relativistic corrections and ...
N. Popov, A. Mysovsky, R. Shendrik, E. Radzhabov   +3 more
openaire   +1 more source

Theoretical study of multi-centre bonding using a delocalised MO approach

Journal of Molecular Structure: THEOCHEM, 1992
Abstract The nature of the bonding in about thirty electron-deficient molecules has been studied on the basis of two-centre and multi-centre (mainly three-centre) bond indices and atomic valencies calculated from ab initio SCF density matrices using 4-31G (or 6-31G) and 6-31G∗ (or 6-31G∗∗) basis sets.
A.B. Sannigrahi, P.K. Nandi, L. Behera, T. Kar   +3 more
openaire   +1 more source

Nurses’ perceived barriers to the delivery of person‐centred care to complex patients: A qualitative study using theoretical domains framework

Journal of Clinical Nursing, 2022
AbstractAims and ObjectivesTo determine nurses’ perceived barriers to the delivery of person‐centred care to complex patients with multiple chronic conditions in acute care settings.BackgroundComplex patients have multiple physical and mental health problems, and their life is also greatly affected by sociocultural and economic determinants of health ...
Ahtisham Younas, Shahzad Inayat, Samuel Masih   +2 more
openaire   +2 more sources

Theoretical studies of the spin Hamiltonian parameters for the tetragonal Cu2+ centres in NaF and CsCdF3

Optik, 2015
Abstract The spin Hamiltonian parameters ( g factors and hyperfine structure constants) for Cu 2+ in NaF and CsCdF 3 are theoretically studied using the high order perturbation formulas of these parameters for a 3d 9 ion in a tetragonally elongated octahedron. The Cu 2+ centres are found to suffer the relative elongation ratios of about 5.5% and
Ming-He Wu, Shao-Yi Wu, Bao-Hua Teng, Zhi-Hong Zhang   +3 more
openaire   +1 more source