The Experts below are selected from a list of 282 Experts worldwide ranked by ideXlab platform
Takahito Nakajima - One of the best experts on this subject based on the ideXlab platform.
-
Relativistic Time-Dependent Density Functional Theory for Molecular Properties
Frontiers of Quantum Chemistry, 2018Co-Authors: Masahiro Kamiya, Takahito NakajimaAbstract:In this review article, we introduce the two-component Relativistic Time-dependent density functional theory (TDDFT) with spin–orbit interactions to calculate linear response properties and excitation energies. The approach is implemented in the NTChem program. Our implementation is based on a noncollinear exchange–correlation potential presented by Wang et al. In addition, various DFT functionals including the range-separated hybrid functionals have been derived and implemented with the aid of a newly developed computerized symbolic algebra system. The two-component Relativistic TDDFT with spin–orbit interactions was successfully applied to the calculation of the frequency-dependent polarizabilities of SnH4 and PbH4 molecules containing heavy atoms and the excitation spectra of a HI molecule.
-
Theoretical study on spin-forbidden transitions of osmium complexes by two-component Relativistic Time-dependent density functional theory
Chemical Physics Letters, 2016Co-Authors: Yutaka Imamura, Muneaki Kamiya, Takahito NakajimaAbstract:Abstract We study spin-forbidden transitions of Os polypyridyl sensitizers by two-component Relativistic Time-dependent density functional theory with the spin–orbit interaction based on Tamm–Dancoff approximation. The absorption spectra, including spin-forbidden-transition peaks, for the Os complexes are reasonably reproduced in comparison with the experimental ones. The extension of the conjugated lengths in the Os complexes is investigated and found to be effective to enhance photo absorption for spin-allowed transitions as well as spin-forbidden ones. This study provides fruitful information for a design of new dyes in terms of conjugation lengths.
-
Two-component Relativistic Time-dependent density functional theory study on spin-forbidden transitions for metal polypyridyl complexes
Chemical Physics Letters, 2015Co-Authors: Yutaka Imamura, Muneaki Kamiya, Takahito NakajimaAbstract:Abstract Spin-forbidden transitions of metal polypyridyl sensitizers are studied by the two-component Relativistic Time-dependent density functional theory with spin–orbit interaction based on Tamm–Dancoff approximation. The spin-forbidden transitions for a phosphine-coordinated Ru(II), DX1, as well as the modified DX1 complexes whose Ru is replaced with Fe and Os, are calculated. The role of the central metals in spin-forbidden transitions is discussed toward the exploration for new efficient sensitizers.
Yutaka Imamura - One of the best experts on this subject based on the ideXlab platform.
-
Theoretical study on spin-forbidden transitions of osmium complexes by two-component Relativistic Time-dependent density functional theory
Chemical Physics Letters, 2016Co-Authors: Yutaka Imamura, Muneaki Kamiya, Takahito NakajimaAbstract:Abstract We study spin-forbidden transitions of Os polypyridyl sensitizers by two-component Relativistic Time-dependent density functional theory with the spin–orbit interaction based on Tamm–Dancoff approximation. The absorption spectra, including spin-forbidden-transition peaks, for the Os complexes are reasonably reproduced in comparison with the experimental ones. The extension of the conjugated lengths in the Os complexes is investigated and found to be effective to enhance photo absorption for spin-allowed transitions as well as spin-forbidden ones. This study provides fruitful information for a design of new dyes in terms of conjugation lengths.
-
Two-component Relativistic Time-dependent density functional theory study on spin-forbidden transitions for metal polypyridyl complexes
Chemical Physics Letters, 2015Co-Authors: Yutaka Imamura, Muneaki Kamiya, Takahito NakajimaAbstract:Abstract Spin-forbidden transitions of metal polypyridyl sensitizers are studied by the two-component Relativistic Time-dependent density functional theory with spin–orbit interaction based on Tamm–Dancoff approximation. The spin-forbidden transitions for a phosphine-coordinated Ru(II), DX1, as well as the modified DX1 complexes whose Ru is replaced with Fe and Os, are calculated. The role of the central metals in spin-forbidden transitions is discussed toward the exploration for new efficient sensitizers.
Muneaki Kamiya - One of the best experts on this subject based on the ideXlab platform.
-
Theoretical study on spin-forbidden transitions of osmium complexes by two-component Relativistic Time-dependent density functional theory
Chemical Physics Letters, 2016Co-Authors: Yutaka Imamura, Muneaki Kamiya, Takahito NakajimaAbstract:Abstract We study spin-forbidden transitions of Os polypyridyl sensitizers by two-component Relativistic Time-dependent density functional theory with the spin–orbit interaction based on Tamm–Dancoff approximation. The absorption spectra, including spin-forbidden-transition peaks, for the Os complexes are reasonably reproduced in comparison with the experimental ones. The extension of the conjugated lengths in the Os complexes is investigated and found to be effective to enhance photo absorption for spin-allowed transitions as well as spin-forbidden ones. This study provides fruitful information for a design of new dyes in terms of conjugation lengths.
-
Two-component Relativistic Time-dependent density functional theory study on spin-forbidden transitions for metal polypyridyl complexes
Chemical Physics Letters, 2015Co-Authors: Yutaka Imamura, Muneaki Kamiya, Takahito NakajimaAbstract:Abstract Spin-forbidden transitions of metal polypyridyl sensitizers are studied by the two-component Relativistic Time-dependent density functional theory with spin–orbit interaction based on Tamm–Dancoff approximation. The spin-forbidden transitions for a phosphine-coordinated Ru(II), DX1, as well as the modified DX1 complexes whose Ru is replaced with Fe and Os, are calculated. The role of the central metals in spin-forbidden transitions is discussed toward the exploration for new efficient sensitizers.
Mauro Stener - One of the best experts on this subject based on the ideXlab platform.
-
L2,3 edge photoabsorption spectra of bulk V2O5: A two components Relativistic Time dependent density functional theory description with finite cluster model
The Journal of chemical physics, 2012Co-Authors: Giovanna Fronzoni, Renato De Francesco, Mauro StenerAbstract:The two-component Relativistic Time dependent density functional theory method to treat the core electron excitations has been applied to the bulk V2O5 for the description of X-ray absorption at the L edges. The theoretical method has proven accurate to reproduce the experimental NEXAFS spectrum, thanks to the inclusion of the most relevant physical effects: the crystal field, the configuration mixing, and the spin-orbit coupling. The method has been applied by taking into account suitable cluster models, accurately chosen in order to simulate at best the electronic structure of the condensed phase.
-
Optical excitations of gold nanoparticles: a quantum chemical scalar Relativistic Time Dependent Density Functional study
The Journal of Physical Chemistry C, 2007Co-Authors: Mauro Stener, A. Nardelli, R. De Francesco, Giovanna FronzoniAbstract:The valence optical excitation spectra of the gold clusters series Au 6 4+ , A u44 4+ , and Au 146 2+ have been calculated at the scalar Relativistic Time dependent density functional theory level. Optical spectra have been calculated at the optimized geometries, the electronic structure has been described in terms of density of states, and optical spectra have been discussed in terms of electronic structure features. The well-known blue shift with decreasing cluster size has been successfully predicted by the theory.
-
Photoionization of mercury: A Relativistic Time-dependent density-functional-theory approach
Physical Review A, 2002Co-Authors: Daniele Toffoli, Mauro Stener, Piero DeclevaAbstract:The Relativistic Time-dependent density functional theory (RTDDFT) has been applied to the photoionization of mercury in the energy range from the threshold up to 300 eV, thus covering almost all the photon energy range for which experimental data are available. Partial cross sections and asymmetry parameter profiles for the 6s, 5d, 5p, and 4f subshells have been calculated and compared with earlier Relativistic random-phase approximation and RTDDFT theoretical calculations and with the experimental results. A study of the spin polarization of photoelectrons from the outer subshells 6s and 5d at RTDDFT level is also presented. The use of the LB94 exchange-correlation potential together with an implementation of the RTDDFT equations in a B-spline basis set based on a noniterative procedure for the calculation of the induced response potential has permitted the study, at RTDDFT level, of the autoionization resonances converging to the 5d 3 / 2 , 5 / 2 and 5p 1 / 2 , 3 / 2 thresholds. Comparison of the RTDDFT results with the other theoretical and experimental data available confirms the effectiveness of the method in the description of correlation and Relativistic effects in the photoionization of such a heavy system.
-
Application of the Relativistic Time-dependent density functional theory to the photoionization of xenon
Journal of Physics B, 2002Co-Authors: Daniele Toffoli, Mauro Stener, Piero DeclevaAbstract:Absolute photoionization cross section profiles, branching ratios and asymmetry parameters of xenon have been calculated with the Time-dependent density functional theory (TDDFT) approach in a wide photon energy range, from threshold up to 740 eV. The Relativistic TDDFT (RTDDFT) equations have been implemented employing a B-spline finite basis set with a non-iterative algorithm for the calculation of the response-induced potential, thus eliminating the well known convergence difficulties associated with their iterative solution. The use of the gradient-dependent LB94 exchange-correlation potential, which allows the existence of bound Rydberg states, has permitted the description, for the first Time at RTDDFT level, of the autoionization resonances. Generally, an excellent reproduction of experimental results is obtained, always at least as accurate as that obtained with the computationally more expensive Relativistic random phase approximation approach, making the B-spline RTDDFT formulation a very promising approach for the calculation of photoionization processes in heavy-atom systems.
Giovanna Fronzoni - One of the best experts on this subject based on the ideXlab platform.
-
L2,3 edge photoabsorption spectra of bulk V2O5: A two components Relativistic Time dependent density functional theory description with finite cluster model
The Journal of chemical physics, 2012Co-Authors: Giovanna Fronzoni, Renato De Francesco, Mauro StenerAbstract:The two-component Relativistic Time dependent density functional theory method to treat the core electron excitations has been applied to the bulk V2O5 for the description of X-ray absorption at the L edges. The theoretical method has proven accurate to reproduce the experimental NEXAFS spectrum, thanks to the inclusion of the most relevant physical effects: the crystal field, the configuration mixing, and the spin-orbit coupling. The method has been applied by taking into account suitable cluster models, accurately chosen in order to simulate at best the electronic structure of the condensed phase.
-
Optical excitations of gold nanoparticles: a quantum chemical scalar Relativistic Time Dependent Density Functional study
The Journal of Physical Chemistry C, 2007Co-Authors: Mauro Stener, A. Nardelli, R. De Francesco, Giovanna FronzoniAbstract:The valence optical excitation spectra of the gold clusters series Au 6 4+ , A u44 4+ , and Au 146 2+ have been calculated at the scalar Relativistic Time dependent density functional theory level. Optical spectra have been calculated at the optimized geometries, the electronic structure has been described in terms of density of states, and optical spectra have been discussed in terms of electronic structure features. The well-known blue shift with decreasing cluster size has been successfully predicted by the theory.
