The Experts below are selected from a list of 207 Experts worldwide ranked by ideXlab platform
Evert Jan Baerends - One of the best experts on this subject based on the ideXlab platform.
-
a simple natural orbital mechanism of pure van der waals interaction in the lowest excited triplet state of the hydrogen molecule
Journal of Chemical Physics, 2006Co-Authors: O V Gritsenko, Evert Jan BaerendsAbstract:A treatment of van der Waals (vdW) interaction by density-matrix functional theory requires a description of this interaction in terms of natural orbitals (NOs) and their occupation numbers. From an analysis of the configuration-interaction (CI) wave function of the 3Sigmau + state of H2 and the exact NO expansion of the two-electron triplet wave function, we demonstrate that the construction of such a functional is straightforward in this case. A quantitative description of the vdW interaction is already obtained with, in addition to the standard part arising from the Hartree-Fock determinant /1sigmag(r1)1sigmau(r2)/, only two additional terms in the two-electron density, one from the first "excited" determinant /2sigmag(r1)2sigmau(r2)/ and one from the state of 3Sigmau + symmetry belonging to the (1pig)1(1piu)1 configuration. The potential-energy curve of the 3Sigmau + state calculated around the vdW minimum with the exact density-matrix functional employing only these eight NOs and NO occupations is in excellent agreement with the full CI one and reproduces well the benchmark potential curve of Kolos and Wolniewicz [J. Chem. Phys. 43, 2429 (1965)]. The corresponding terms in the two-electron density rho2(r1,r2), containing specific products of NOs combined with prefactors that depend on the occupation numbers, can be shown to produce exchange-correlation holes that correspond precisely to the well-known intuitive picture of the dispersion interaction as an instantaneous dipole-induced dipole (higher multipole) effect. Indeed, (induced) higher multipoles account for almost 50% of the total vdW bond energy. These results serve as a basis for both a density-matrix functional theory of van der Waals bonding and for the construction of orbital-dependent functionals in density-functional theory that could be used for this type of bonding.
Ch Jungen - One of the best experts on this subject based on the ideXlab platform.
-
Experimental and theoretical study of the npπ1Πu- (n⩾4n⩾4) excited states of D2: absolute absorption cross sections and branching ratios for ionization, dissociation and fluorescence
'Elsevier BV', 2015Co-Authors: Glass-maujean Michèle, Vasserot A-m, Ch Jungen, Schmoranzer H, Knie A, Kübler S, Ehresmann AAbstract:International audienceThe absolute absorption cross section and the branching ratios for the competing decay channels fluorescence, dissociation, and ionization of photoexcited long-lived View the MathML source1Πu- superexcited molecular levels in D2 have been measured with a spectral resolution of 0.001 nm from the ionization threshold of D2 up to the D(n=1n=1)+D(n=3n=3) dissociation limit. The experimental energies and absorption line intensities are compared with fully ab initio multichannel quantum defect theory (MQDT) calculations [1] which are based on quantum-chemical potential energy curves and transition moments of Wolniewicz and collaborators [2] and [3]. The overall agreement between experiment and theory is good. The branching ratios for the competing decay channels are also reproduced by the calculations including their substantial variations from level to level. A comparison of the vibronic interactions in the isotopomers H2 and D2 is made
-
multichannel quantum defect theory of double minimum 1 sigma g states in h2 i potential energy curves
Physical Review A, 1994Co-Authors: Stephen C Ross, Ch JungenAbstract:Multichannel quantum-defect theory is applied to the highly accurate [sup 1][Sigma][sub [ital g]][sup +] [ital ab] [ital initio] excited-state potential-energy curves calculated by Wolniewicz and Dressler [J. Chem. Phys. 82, 3262 (1985); and (private communication)]. We show that the three double-minimum states, [ital EF], [ital GK], and [ital H[bar H]], can be represented to within 8 cm[sup [minus]1] by a smooth [ital R]-dependent 3[times]3 nondiagonal quantum-defect matrix. This quantum-defect matrix corresponds to a collision of the Rydberg electron with the H[sub 2][sup +] target, which may be in either the 1[sigma][sub [ital g]] or 1[sigma][sub [ital u]] state. Also discussed is the use of this quantum-defect matrix to calculate diabatic states, more highly excited Born-Oppenheimer states, and the electronic ionization width of the superexcited (1[sigma][sub [ital u]])[sup 2] doubly excited state.
O V Gritsenko - One of the best experts on this subject based on the ideXlab platform.
-
a simple natural orbital mechanism of pure van der waals interaction in the lowest excited triplet state of the hydrogen molecule
Journal of Chemical Physics, 2006Co-Authors: O V Gritsenko, Evert Jan BaerendsAbstract:A treatment of van der Waals (vdW) interaction by density-matrix functional theory requires a description of this interaction in terms of natural orbitals (NOs) and their occupation numbers. From an analysis of the configuration-interaction (CI) wave function of the 3Sigmau + state of H2 and the exact NO expansion of the two-electron triplet wave function, we demonstrate that the construction of such a functional is straightforward in this case. A quantitative description of the vdW interaction is already obtained with, in addition to the standard part arising from the Hartree-Fock determinant /1sigmag(r1)1sigmau(r2)/, only two additional terms in the two-electron density, one from the first "excited" determinant /2sigmag(r1)2sigmau(r2)/ and one from the state of 3Sigmau + symmetry belonging to the (1pig)1(1piu)1 configuration. The potential-energy curve of the 3Sigmau + state calculated around the vdW minimum with the exact density-matrix functional employing only these eight NOs and NO occupations is in excellent agreement with the full CI one and reproduces well the benchmark potential curve of Kolos and Wolniewicz [J. Chem. Phys. 43, 2429 (1965)]. The corresponding terms in the two-electron density rho2(r1,r2), containing specific products of NOs combined with prefactors that depend on the occupation numbers, can be shown to produce exchange-correlation holes that correspond precisely to the well-known intuitive picture of the dispersion interaction as an instantaneous dipole-induced dipole (higher multipole) effect. Indeed, (induced) higher multipoles account for almost 50% of the total vdW bond energy. These results serve as a basis for both a density-matrix functional theory of van der Waals bonding and for the construction of orbital-dependent functionals in density-functional theory that could be used for this type of bonding.
Stephen C Ross - One of the best experts on this subject based on the ideXlab platform.
-
multichannel quantum defect theory of double minimum 1 sigma g states in h2 i potential energy curves
Physical Review A, 1994Co-Authors: Stephen C Ross, Ch JungenAbstract:Multichannel quantum-defect theory is applied to the highly accurate [sup 1][Sigma][sub [ital g]][sup +] [ital ab] [ital initio] excited-state potential-energy curves calculated by Wolniewicz and Dressler [J. Chem. Phys. 82, 3262 (1985); and (private communication)]. We show that the three double-minimum states, [ital EF], [ital GK], and [ital H[bar H]], can be represented to within 8 cm[sup [minus]1] by a smooth [ital R]-dependent 3[times]3 nondiagonal quantum-defect matrix. This quantum-defect matrix corresponds to a collision of the Rydberg electron with the H[sub 2][sup +] target, which may be in either the 1[sigma][sub [ital g]] or 1[sigma][sub [ital u]] state. Also discussed is the use of this quantum-defect matrix to calculate diabatic states, more highly excited Born-Oppenheimer states, and the electronic ionization width of the superexcited (1[sigma][sub [ital u]])[sup 2] doubly excited state.
Mirosławski Mateusz - One of the best experts on this subject based on the ideXlab platform.
-
Teodycea a logika modalna. Bogusława Wolniewicza polemika z krytyką teodycei u Pierre’a Bayle’a
'Pontifical University of John Paul II in Krakow', 2018Co-Authors: Mirosławski MateuszAbstract:The essay aims at presenting original ideas of Bogusław Wolniewicz in the field of modal logic, which improve the traditional theodicy, criticized by Pierre Bayle. The classical theodicy attempts to reconcile divine omnipotence and God’s goodness. According to classical theodicy both of these elements can be reconciled, because evil is not the work of God, but a work of man – freedom is in fact necessary for a man so that he could do good, but to do good, a person automatically has to be able to do the evil (understood morally, not physically). Bayle’s argument says that freedom implies the possibility of evil and it does not imply its existence, and this means that evil can be avoided even with the assumption of freedom. Wolniewicz tries to refute that argument. He quotes a little known definitions of possibility derived from the logic of Megarian. It turns out to be an inspiration for him to introduce an original definition of possibility – “what is possible = what happened or what will happen in the future.” With this interpretation of possibility classic theodicy seems to be efficient.Referat ma na celu zaprezentowanie oryginalnych pomysłów Bogusława Wolniewicza z dziedziny logiki modalnej, które służą usprawnieniu tradycyjnej teodycei, krytykowanej przez Pierre'a Bayle'a. Klasyczna teodycea stara się pogodzić boską wszechmoc z bożą dobrocią. Według klasycznej teodycei oba te elementy dają się pogodzić, ponieważ zło nie jest dziełem Boga, lecz człowieka – wolność jest bowiem konieczna dla człowieka, aby ten mógł czynić dobro, ale aby czynić dobro, człowiek automatycznie musi móc czynić także zło (rozumiane moralnie, nie fizycznie). Argumentacja Bayle'a mówi natomiast, że choć wolność implikuje możliwość zła, to nie implikuje jednak jego istnienia, a to oznacza, że zła można uniknąć nawet przy założeniu wolności. Wolniewicz stara się obalić tę argumentację. W tym celu przywołuje on mało znane definicje możliwości wywodzące się z logiki megarejskiej, które dostarczają inspiracji do wprowadzenia oryginalnej definicji możliwości – „to co możliwe = to, co się zdarzyło lub to co zdarzy się w przyszłości". Przy takiej interpretacji modalnej teodycea klasyczna wydaje się być sprawn
-
Teodycea a logika modalna. Bogusława Wolniewicza polemika z krytyką teodycei u Pierre’a Balye’a
'Pontifical University of John Paul II in Krakow', 2017Co-Authors: Mirosławski MateuszAbstract:The essay aims at presenting original ideas of Bogusław Wolniewicz in the field of modal logic, which improve the traditional theodicy, criticized by Pierre Bayle. The classical theodicy attempts to reconcile divine omnipotence and God’s goodness. According to classical theodicy both of these elements can be reconciled, because evil is not the work of God, but a work of man – freedom is in fact necessary for a man so that he could do good, but to do good, a person automatically has to be able to do the evil (understood morally, not physically). Bayle’s argument says that freedom implies the possibility of evil and it does not imply its existence, and this means that evil can be avoided even with the assumption of freedom. Wolniewicz tries to refute that argument. He quotes a little known definitions of possibility derived from the logic of Megarian. It turns out to be an inspiration for him to introduce an original definition of possibility – “what is possible = what happened or what will happen in the future.” With this interpretation of possibility classic theodicy seems to be efficient
