Electric quadrupole and hexadecapole moment, dipole polarizability and hyperpolarizability of the copper tetramer (Cu4) from pseudopotential calculations and a comparison with all-electron ab initio results

2012 ◽  
Vol 988 ◽  
pp. 34-41 ◽  
Author(s):  
George Maroulis ◽  
Anastasios Haskopoulos
Keyword(s):  
Ab Initio ◽  
Electric Quadrupole ◽  
Dipole Polarizability ◽  
Pseudopotential Calculations

Ab initio band theory approach to electron energy loss near edge structures

1988 ◽  
Vol 46 ◽  
pp. 506-507
Author(s):  
Xudong Weng ◽  
O.F. Sankey ◽  
Peter Rez
Keyword(s):  
Ab Initio ◽  
Local Density ◽  
Interpolation Method ◽  
Atomic Orbital ◽  
Plane Waves ◽  
Large Set ◽  
Theory Approach ◽  
Band Theory ◽  
Atomic Orbitals ◽  
Pseudopotential Calculations

Single electron band structure techniques have been applied successfully to the interpretation of the near edge structures of metals and other materials. Among various band theories, the linear combination of atomic orbital (LCAO) method is especially simple and interpretable. The commonly used empirical LCAO method is mainly an interpolation method, where the energies and wave functions of atomic orbitals are adjusted in order to fit experimental or more accurately determined electron states. To achieve better accuracy, the size of calculation has to be expanded, for example, to include excited states and more-distant-neighboring atoms. This tends to sacrifice the simplicity and interpretability of the method.In this paper. we adopt an ab initio scheme which incorporates the conceptual advantage of the LCAO method with the accuracy of ab initio pseudopotential calculations. The so called pscudo-atomic-orbitals (PAO's), computed from a free atom within the local-density approximation and the pseudopotential approximation, are used as the basis of expansion, replacing the usually very large set of plane waves in the conventional pseudopotential method. These PAO's however, do not consist of a rigorously complete set of orthonormal states.

Full Optical Rotation Tensor at CCSD Level in the Modified Velocity Gauge

2020 ◽  
Author(s):  
Kaihua Zhang ◽  
Ty Balduf ◽  
Marco Caricato
Keyword(s):  
Electric Dipole ◽  
Optical Rotation ◽  
Electric Quadrupole ◽  
Polarizability Tensor ◽  
Dipole Polarizability ◽  
Difficult Case ◽  
Computationally Efficient ◽  
Rotation Tensor ◽  
Approximate Methods ◽  
Velocity Gauge

<div> <div> <p> </p><div> <div> <div> <p>This work presents the first simulations of the full optical rotation (OR) tensor at coupled cluster with single and double excitations (CCSD) level in the modified velocity gauge (MVG) formalism. The CCSD-MVG OR tensor is origin independent, and each tensor element can in principle be related directly to experimental measurements on oriented systems. We compare the CCSD results with those from two density functionals, B3LYP and CAM-B3LYP, on a test set of 22 chiral molecules. The results show that the functionals consistently overestimate the CCSD results for the individual tensor components and for the trace (which is related to the isotropic OR), by 10-20% with CAM-B3LYP and 20-30% with B3LYP. The data show that the contribution of the electric dipole-magnetic dipole polarizability tensor to the OR tensor is on average twice as large as that of the electric dipole-electric quadrupole polarizability tensor. The difficult case of (1S,4S)-(–)-norbornenone also reveals that the evaluation of the former polarizability tensor is more sensitive than the latter. We attribute the better agreement of CAM-B3LYP with CCSD to the ability of this functional to better reproduce electron delocalization compared with B3LYP, consistently with previous reports on isotropic OR. The CCSD-MVG approach allows the computation of reference data of the full OR tensor, which may be used to test more computationally efficient approximate methods that can be employed to study realistic models of optically active materials. </p> </div> </div> </div> </div> </div>

scholarly journals Density functional studies of the dipole polarizabilities of the linear polyacenes benzene through nonacene

2005 ◽  
Vol 3 (2) ◽  
pp. 361-369 ◽  
Author(s):  
Alan Hinchliffe ◽  
Beatrice Nikolaidi ◽  
Humberto Soscún Machado
Keyword(s):  
Ab Initio ◽  
Density Functional ◽  
Correlation Coefficients ◽  
Statistical Correlation ◽  
Tensor Component ◽  
Dipole Polarizability ◽  
Functional Studies ◽  
Absolute Agreement ◽  
Different Levels ◽  
Dipole Polarizabilities

AbstractWe report Ab Initio studies of the electric dipole polarizability of the linear polyacene series benzene through nonacene. A number of Ab Initio studies were done at different levels of theory for benzene, with all remaining Ab Initio calculations being at the B3LYP/6-311G(2d, 1p)//B3LYP/6-311+G(2d, 1p) level of theory. We find that the NN tensor component shows a constant increment of 20 atomic units per ring. AM1 and QSAR-quality empirical calculations show poor absolute agreement with the Ab Initio results but given excellent statistical correlation coefficients with the Ab Initio values. This implies that the results of such cheaper calculations can be suitably scaled for predictive purposes.

Electric Quadrupole Moment of the 14N Nucleus Determined by ab initio Cl Calculation on NH3

1986 ◽  
Vol 41 (1-2) ◽  
pp. 163-165 ◽  
Author(s):  
Tae-Kyu Ha
Keyword(s):  
Electric Field Gradient ◽  
Ab Initio ◽  
Electric Quadrupole ◽  
Quadrupole Coupling Constant ◽  
Basis Set ◽  
Electric Quadrupole Moment ◽  
Coupling Constant ◽  
Hartree Fock ◽  
Quadrupole Coupling ◽  
Constant E

Based on the calculated electric field gradient (q) from ab initio Cl wavefunctions with largebasis set (including ƒ functions on N and d functions on H) and the experimental nuclearquadrupole coupling constant (e Q q) for nitrogen in NH3, an improved value o f the quadrupole moment of 14N is proposed as Q (14N ) = 2.08 x 10-26cm2. The value calculated using a wavefunctionnear the Hartree-Fock limit enlarged ≈ 10% by the Cl treatment.

Surface Diffusion and Incorporation Process of Adatom in Fe-Al Multilayer System

2006 ◽  
Vol 317-318 ◽  
pp. 411-414 ◽  
Author(s):  
Chi Ho Kim ◽  
In Yong Kang ◽  
Yong Chae Chung
Keyword(s):  
Total Energy ◽  
Ab Initio ◽  
Surface Diffusion ◽  
Energy Barrier ◽  
Energy Gain ◽  
Multilayer System ◽  
Large Energy ◽  
Hollow Site ◽  
Pseudopotential Calculations ◽  
Adsorption Energies

Using the ab initio pseudopotential calculations, the surface diffusion and incorporation process at the interface of Fe-Al multilayer system were quantitatively investigated. The hollow site was most stable adsorption site on both Al (001) and Fe (001) surface. The adsorption energies were 8.62 eV for Fe/Al (001) and 5.30 eV for Al/Fe (001) system. The calculated energy barriers for the surface diffusion of adatom were 0.89 eV and 0.61 eV for each system. The energy barrier for the incorporation of Fe adatom into the Al substrate was calculated to be 0.38 eV and the energy gain of the system was 0.49 eV. However, the Al adatom required relatively large energy barrier, 0.99 eV for the incorporation into the Fe substrate resulting in 0.13 eV increase in total energy of the system.

Ab initio and density functional theory calculations of the dipole polarizability and the second dipole hyperpolarizability of benzene

2002 ◽  
Vol 90 (2) ◽  
pp. 497-506 ◽  
Author(s):  
Humberto Soscún ◽  
Javier Hernández ◽  
Ramón Escobar ◽  
Carlos Toro-Mendoza ◽  
Ysaías Alvarado ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Ab Initio ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Dipole Polarizability ◽  
Functional Theory
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