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Zdenek Stuchlik - One of the best experts on this subject based on the ideXlab platform.
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optical Reference Geometry and inertial forces in kerr de sitter spacetimes
arXiv: General Relativity and Quantum Cosmology, 2007Co-Authors: Jiri Kovar, Zdenek StuchlikAbstract:Optical Reference Geometry and related concept of inertial forces are investigated in Kerr-de Sitter spacetimes. Properties of the inertial forces are summarized and their typical behaviour is illustrated. The intuitive 'Newtonian' application of the forces in the relativistic dynamics is demonstrated in the case of the test particle circular motion, static equilibrium positions and perfect fluid toroidal configurations. Features of the optical Geometry are illustrated by the embedding diagrams of its equatorial plane. The embedding diagrams do not cover whole the stationary regions of the spacetimes, therefore the limits of embeddability are established. A shape of the embedding diagrams is related to the behaviour of the centrifugal force and it is characterized by the number of turning points of the diagrams. Discussion of the number of embeddable photon circular orbits is also included and the typical embedding diagrams are constructed. The Kerr-de Sitter spacetimes are classified according to the properties of the inertial forces and embedding diagrams.
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forces in kerr spacetimes with a repulsive cosmological constant
arXiv: General Relativity and Quantum Cosmology, 2006Co-Authors: Jiri Kovar, Zdenek StuchlikAbstract:Forces defined in the framework of optical Reference Geometry are introduced in the case of stationary and axially symmetric Kerr black-hole and naked-singularity spacetimes with a repulsive cosmological constant. Properties of the forces acting on test particles moving along circular orbits in the equatorial plane are discussed, whereas it is shown where the gravitational force vanishes and changes its orientation and where the centrifugal force vanishes and changes its orientation independently of the velocity of test particles related to the optical Geometry; the Coriolis force does not vanish for the velocity being non-zero. The spacetimes are classified according to the number of circular orbits where the gravitational and centrifugal forces vanish.
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optical Reference Geometry of kerr newman spacetimes
Classical and Quantum Gravity, 2000Co-Authors: Zdenek Stuchlik, Stanislav Hledik, J JuranAbstract:Properties of the optical Reference Geometry related to Kerr-Newman black-hole and naked-singularity spacetimes are illustrated using embedding diagrams of their equatorial plane. It is shown that among all inertial forces defined within the framework of the optical Geometry, just the centrifugal force plays a fundamental role in connection with the embedding diagrams because it changes sign at the turning points of the diagrams. The embedding diagrams do not cover the stationary part of the Kerr-Newman spacetimes completely. Hence, the limits of embeddability are given, and it is established which of the photon circular orbits hosted by the Kerr-Newman spacetimes appear in the embeddable regions. Some typical embedding diagrams are constructed, and the Kerr-Newman backgrounds are classified according to the number of embeddable regions of the optical Geometry as well as the number of their turning points. It is shown that embedding diagrams are closely related to the notion of the radius of gyration which is useful for analysing a fluid rotating in strong gravitational fields.
Andrzej L Sobolewski - One of the best experts on this subject based on the ideXlab platform.
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characterization of the s1 s2 conical intersection in pyrazine using ab initio multiconfiguration self consistent field and multiReference configuration interaction methods
Journal of Chemical Physics, 1994Co-Authors: Clemens Woywod, Wolfgang Domcke, Andrzej L SobolewskiAbstract:Potential‐energy surfaces of the three lowest singlet states of pyrazine have been calculated as a function of ab initio determined ground‐state normal coordinates, using complete‐active‐space self‐consistent‐field (CASSCF) and multiReference configuration interaction (MRCI) techniques. The conical intersection of the S1 and S2 adiabatic potential‐energy surfaces has been mapped out in selected subspaces spanned by the most relevant vibrational coordinates. A unitary transformation from the adiabatic to a quasidiabatic electronic representation is performed, which eliminates the rapid variations of the wave functions responsible for the singularity of the nonadiabatic coupling element. Transition‐dipole‐moment functions have been obtained in the adiabatic and in the diabatic representation. The leading coefficients of the Taylor expansion of the diabatic potential‐energy and transition‐dipole‐moment surfaces in terms of ground‐state normal coordinates at the Reference Geometry have been obtained at the CA...
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characterization of the s1 s2 conical intersection in pyrazine using ab initio multiconfiguration self consistent field and multiReference configuration interaction methods
Journal of Chemical Physics, 1994Co-Authors: Clemens Woywod, Wolfgang Domcke, Andrzej L Sobolewski, Hansjoachim WernerAbstract:Potential‐energy surfaces of the three lowest singlet states of pyrazine have been calculated as a function of ab initio determined ground‐state normal coordinates, using complete‐active‐space self‐consistent‐field (CASSCF) and multiReference configuration interaction (MRCI) techniques. The conical intersection of the S1 and S2 adiabatic potential‐energy surfaces has been mapped out in selected subspaces spanned by the most relevant vibrational coordinates. A unitary transformation from the adiabatic to a quasidiabatic electronic representation is performed, which eliminates the rapid variations of the wave functions responsible for the singularity of the nonadiabatic coupling element. Transition‐dipole‐moment functions have been obtained in the adiabatic and in the diabatic representation. The leading coefficients of the Taylor expansion of the diabatic potential‐energy and transition‐dipole‐moment surfaces in terms of ground‐state normal coordinates at the Reference Geometry have been obtained at the CASSCF/MRCI level. Using a vibronic‐coupling model Hamiltonian based on this Taylor expansion, the absorption spectrum of the interacting S1–S2 manifold has been calculated, taking account of the four spectroscopically most relevant modes.
Clemens Woywod - One of the best experts on this subject based on the ideXlab platform.
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characterization of the s1 s2 conical intersection in pyrazine using ab initio multiconfiguration self consistent field and multiReference configuration interaction methods
Journal of Chemical Physics, 1994Co-Authors: Clemens Woywod, Wolfgang Domcke, Andrzej L SobolewskiAbstract:Potential‐energy surfaces of the three lowest singlet states of pyrazine have been calculated as a function of ab initio determined ground‐state normal coordinates, using complete‐active‐space self‐consistent‐field (CASSCF) and multiReference configuration interaction (MRCI) techniques. The conical intersection of the S1 and S2 adiabatic potential‐energy surfaces has been mapped out in selected subspaces spanned by the most relevant vibrational coordinates. A unitary transformation from the adiabatic to a quasidiabatic electronic representation is performed, which eliminates the rapid variations of the wave functions responsible for the singularity of the nonadiabatic coupling element. Transition‐dipole‐moment functions have been obtained in the adiabatic and in the diabatic representation. The leading coefficients of the Taylor expansion of the diabatic potential‐energy and transition‐dipole‐moment surfaces in terms of ground‐state normal coordinates at the Reference Geometry have been obtained at the CA...
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characterization of the s1 s2 conical intersection in pyrazine using ab initio multiconfiguration self consistent field and multiReference configuration interaction methods
Journal of Chemical Physics, 1994Co-Authors: Clemens Woywod, Wolfgang Domcke, Andrzej L Sobolewski, Hansjoachim WernerAbstract:Potential‐energy surfaces of the three lowest singlet states of pyrazine have been calculated as a function of ab initio determined ground‐state normal coordinates, using complete‐active‐space self‐consistent‐field (CASSCF) and multiReference configuration interaction (MRCI) techniques. The conical intersection of the S1 and S2 adiabatic potential‐energy surfaces has been mapped out in selected subspaces spanned by the most relevant vibrational coordinates. A unitary transformation from the adiabatic to a quasidiabatic electronic representation is performed, which eliminates the rapid variations of the wave functions responsible for the singularity of the nonadiabatic coupling element. Transition‐dipole‐moment functions have been obtained in the adiabatic and in the diabatic representation. The leading coefficients of the Taylor expansion of the diabatic potential‐energy and transition‐dipole‐moment surfaces in terms of ground‐state normal coordinates at the Reference Geometry have been obtained at the CASSCF/MRCI level. Using a vibronic‐coupling model Hamiltonian based on this Taylor expansion, the absorption spectrum of the interacting S1–S2 manifold has been calculated, taking account of the four spectroscopically most relevant modes.
J Juran - One of the best experts on this subject based on the ideXlab platform.
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optical Reference Geometry of kerr newman spacetimes
Classical and Quantum Gravity, 2000Co-Authors: Zdenek Stuchlik, Stanislav Hledik, J JuranAbstract:Properties of the optical Reference Geometry related to Kerr-Newman black-hole and naked-singularity spacetimes are illustrated using embedding diagrams of their equatorial plane. It is shown that among all inertial forces defined within the framework of the optical Geometry, just the centrifugal force plays a fundamental role in connection with the embedding diagrams because it changes sign at the turning points of the diagrams. The embedding diagrams do not cover the stationary part of the Kerr-Newman spacetimes completely. Hence, the limits of embeddability are given, and it is established which of the photon circular orbits hosted by the Kerr-Newman spacetimes appear in the embeddable regions. Some typical embedding diagrams are constructed, and the Kerr-Newman backgrounds are classified according to the number of embeddable regions of the optical Geometry as well as the number of their turning points. It is shown that embedding diagrams are closely related to the notion of the radius of gyration which is useful for analysing a fluid rotating in strong gravitational fields.
Hans Lischka - One of the best experts on this subject based on the ideXlab platform.
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the charge transfer states in a stacked nucleobase dimer complex a benchmark study
Journal of Computational Chemistry, 2011Co-Authors: Adelia J A Aquino, Dana Nachtigallova, Pavel Hobza, Donald G Truhlar, Christof Hattig, Hans LischkaAbstract:: Electronic singlet excitations of stacked adenine-thymine (AT) and guanine-cytosine (GC) complexes have been investigated with respect to local excitation and charge-transfer (CT) characters. Potential energy curves for rigid displacement of the nucleobases have been computed to establish the distance dependence of the CT states. The second-order algebraic diagrammatic construction [ADC(2)] method served as Reference approach for comparison to a selected set of density functionals used within the time-dependent density functional theory (TD-DFT). Particular attention was dedicated to the performance of the recently developed family of M06 functionals. The calculations for the stacked complexes show that at the ADC(2) level, the lowest CT state is S(6) for the AT and as S(4) for the GC pair. At the Reference Geometry, the actual charge transferred is found to be 0.73 e for AT. In case of GC, this amount is much smaller (0.17 e). With increasing separation of the two nucleobases, the CT state is strongly destabilized. The M06-2X version provides a relatively good reproduction of the ADC(2) results. It avoids the serious overstabilization and overcrowding of the spectrum found with the B3LYP functional. On the other hand, M06-HF destabilizes the CT state too strongly. TD-DFT/M06-2X calculations in solution (heptane, isoquinoline, and water) using the polarizable continuum model show a stabilization of the CT state and an increase in CT character with increasing polarity of the solvent.