Rosa Caballol - Academia.edu (original) (raw)
Papers by Rosa Caballol
Physical Review Letters, Nov 22, 1993
Chemical Physics Letters, Apr 1, 1990
Physical Chemistry Chemical Physics, 2015
This work explores the electronic structure aspects involving the complete intermolecular O2 tran... more This work explores the electronic structure aspects involving the complete intermolecular O2 transfer between Ni (II) and Mn (II) complexes, both containing Ntetramethylated cyclams (TMC). The energy of the low-lying states of reactants, intermediates and products is established at the CASSCF level and also the DDCI level when possible. The orthogonal valence bond analysis of the wave functions obtained from CASSCF and DDCI calculations indicates the dominant superoxide nature of all the adducts participating in the reaction, and consequently that th whole reaction can be described as the transfer of the superoxide O2− between Ni (II) and Mn (II) complexes, without any additional change in the electronic structure of the fragments.
Journal of Computational Chemistry, Jan 15, 1996
ABSTRACT The relative stability of the 3A2, 1A2, and 1A1 states of phenylnitrene is evaluated by ... more ABSTRACT The relative stability of the 3A2, 1A2, and 1A1 states of phenylnitrene is evaluated by means of ab initio calculations followed by difference-dedicated configuration interaction (DDCI). This approach is based on effective Hamiltonian theory at a low order of perturbation to select rationally the determinants which contribute to the energy difference. The CI space built on this criterion is then treated variationally. The method allows a considerable reduction of the CI space compared with a complete CAS*SDCI calculation (where CAS stands for complete active space). Depending on the concerned energy difference, different model spaces may be chosen, as illustrated in the 3A2 → 1A2 and the 3A2 → 1A1 transitions in phenylnitrene. Since the CI space may reach considerable dimensions, a direct CI algorithm for selected CI spaces, the SCIEL algorithm, has been used to perform the calculations. The results are in excellent agreement with previous calculations and with available experimental data. © 1996 by John Wiley & Sons, Inc.
Journal de chimie physique, 1973
On construit les cartes conformationnelles de la glycine neutre et (le son zwitterion, au moyen d... more On construit les cartes conformationnelles de la glycine neutre et (le son zwitterion, au moyen de la méthode de Scheraga et de la méthode de Hückel étendue. De la comparaison des résultats, on déduit que les deux procédés fournissent une information semblable
Chemischer Informationsdienst, Nov 18, 1986
Physical Review Letters, Apr 18, 1994
ChemInform, Feb 7, 2014
ChemInform Abstract Die durch Kondensation von Pyridin-2-carbaldehyd, Salicylaldehyd oder Acetyla... more ChemInform Abstract Die durch Kondensation von Pyridin-2-carbaldehyd, Salicylaldehyd oder Acetylaceton mit den Diaminoalkanolen gebildeten Liganden reagieren mit Cu-Salzen in Gegenwart der Brücken-bildenden Pyrazolat-und Acetat-Ionen zu den Komplexen (I)-(IV). Pyrazol tauscht auch Einatombrücken in einigen Fällen aus, wie an der Darstellung der Komplexe (I) bzw. (IVa) durch Zugabe von Pyrazol zu den Hydroxo-bzw. Methoxo-verbrückten Komplexen demonstriert wird. Der Komplex (III) (n: 1, XAX: Pyrazolat) wird röntgenographisch (RG Pbcn; Z=8) charakterisiert. Er zeigt keine intermolekularen Wechselwirkungen zwischen benachbarten Einheiten; der intramolekulare Cu-Cu-Abstand beträgt 3.359å. Magnetische Suszeptibilitäten werden für alle Verbindungen im festen Zustand im Temp.-Bereich 4.2-3OO K gemessen. Ein Vergleich der magnetischen Daten dieser Zweiatom-Brücken-Spezies mit analogen Einatom-Brücken-Spezies zeigt, dass-J in der Reihe OR'-pyrazolat acetat a-OH' C1' sinkt (Ausb.-Angaben in g).
Journal of Computational Chemistry, Nov 4, 2010
Highlight To the best of our knowledge we present the first study on the relative interface ene... more Highlight To the best of our knowledge we present the first study on the relative interface energies of coherent and semi-coherent oxide/III-V semiconductor interfaces. The HfO2/GaAs(100) and HfO2/GaP(100) interfaces are investigated. The coherent and semicoherent interfaces represent the main interfacial structural building blocks, Ga-O-Ga bridges and As (P) dimers, respectively. We consider several qualitatively different interfaces based on different oxide types. We present first realistic defect gap state free models for the HfO2/III-V interfaces. Various coherent and semi-coherent interfaces are stable and have band gaps free of defect states in spite of the interfacial structural defects. Defect energetics is discussed. Interface thermodynamics is not responsible for the possible formation of the semi-coherent interfaces including As (P) dimers. The dimers have previously been taken responsible for the harmful Fermi level pinning. Kinetics via the layer by layer growth favors semi-coherent interfaces under the relevant relatively O-rich growth conditions. This is explained by the interface bonding and the electron counting rule (ECR). The same reasoning is used to explain, why ordered oxidized III-V substrates can be used to decrease the interface defect density by a factor of 40 (previously reported to HfO2/InAs).
Physical Review B, Jan 11, 2005
Quantum chemical calculations on embedded cluster models have been performed to extract accurate ... more Quantum chemical calculations on embedded cluster models have been performed to extract accurate estimates of the magnetic coupling J and hopping parameters t of CaCu 2 O 3. It is shown that this copper oxide compound is best described as a quasi-one-dimensional spin chain with weak interchain interactions within and between the Cu 2 O 3 planes. This magnetic structure is not reflected in the hopping parameters, since we find a large interplane hopping. Hence, the use of the simple second-order expression that relates J, t, and the on-site repulsion U ͑J =−4t 2 / U͒ is not justified in all cases.
Origins of Life, 1976
A theoretical methodology for the systematic study of the interstellar molecules is proposed. Som... more A theoretical methodology for the systematic study of the interstellar molecules is proposed. Some examples, dealing with formaldehyde excited states, formyl radical and ion, reactivity of the excited states of formic acid, methyl cyanide and methyl acetylene, as well as the reaction patho of formaldehyde photodecomposition are presented. Quantum chemical methods appear to be a powerful tool to study the structure and behaviour of molecules related with interstellar space and the Origin of Life.
Chemical Physics Letters, 2008
ABSTRACT The magnetic coupling in the manganese dimer has been investigated with multiconfigurati... more ABSTRACT The magnetic coupling in the manganese dimer has been investigated with multiconfigurational computational schemes. Whereas the perturbational approaches present severe deviations to the expected Heisenberg behaviour, variational techniques based on difference dedicated configuration interaction (DDCI) perfectly fit a Heisenberg spectrum corresponding to antiferromagnetic coupling. This shows that the study of weak magnetic coupling as in Mn(2) is at (or beyond) the limit of applicability of perturbational techniques. Potential energy curves are obtained for the six low-lying R states by adding the DDCI energy difference to the reference potential energy surface calculated with coupled cluster techniques for the monoconfigurational 11 Sigma(+)(g) g state. (c) 2008 Elsevier B.V. All rights reserved.
Journal of Chemical Physics, Jul 8, 1998
The iterative difference dedicated configuration interaction (IDDCI) method, recently proposed fo... more The iterative difference dedicated configuration interaction (IDDCI) method, recently proposed for calculating excited electronic states, is tested in systems where the core-valence correlation plays an important role. The calculated ionization potential, electron affinity, and electronic transition energies of K and Rb agree within 0.1 eV with experimental values. The three lowest Σ+ potential curves of KH and RbH and the six lowest states Σg+, Σu+, and Πu of K2 are calculated with the same accuracy.
Chemical Physics Letters, 1987
Ab initio calculations using pseudopotentials and configuration interaction (CI) are performed on... more Ab initio calculations using pseudopotentials and configuration interaction (CI) are performed on H3Y…HX (Y=P, As; X =Cl, Br) hydrogen-bonded complexes. Electron correlation plays an important role in determining the binding energy as well as the Y…H distance. The binding energies range from 2.64 to 1.43 kcal mol−1, from second- to third-row complexes.
Inorganic Chemistry, 1996
Ab initio DDCI2 (difference-dedicated configuration interaction) calculations are performed on th... more Ab initio DDCI2 (difference-dedicated configuration interaction) calculations are performed on the exchange coupling constant of the doubly-bridged Ni(II) complexes [Ni(en) 2 Cl] 2 2+ and [Ni(terpy)(N 3)] 2 2+ , which are modeled by substituting the external ligands with ammonia groups. The variational CI space is selected on the grounds of the effective Hamiltonian theory and includes all the second-order contributions to the difference between the lowest quintet, triplet, and singlet states. Both complexes are found to be ferromagnetic, with coupling constants of 1.8 and 21.1 cm-1 , in good agreement with the experiment. A transformation of the molecular orbitals is also proposed for large systems, enabling the molecular orbital set to be significantly truncatedsas well as the file of two-electron integrals and the DDCI2 spaceswith no loss of efficiency.
Journal de Chimie Physique, 1974
17 Espagne.) (Manuscrit reçu le 13.11.73.) SOMMAIRE L'analyse conformationnelle des éthylamines p... more 17 Espagne.) (Manuscrit reçu le 13.11.73.) SOMMAIRE L'analyse conformationnelle des éthylamines polychorées est effectuée au moyen de la méthode de Hückel étendue. On calcule les barrières de rotation concernant les deux degrés de rotation dans les amines et les ions correspondants. La méthode EH fournit un bon accord avec les résultats expé rimentaux, ainsi qu'avec les calculs « ah initio ».
Chemischer Informationsdienst, 1974
The Difference Dedicated Configuration Interaction method is described and its performance illust... more The Difference Dedicated Configuration Interaction method is described and its performance illustrated by applications on electronic transitions, singlettriplet separations and magnetic exchange coupling.
Physical Review B, 2005
Quantum chemical calculations on embedded cluster models have been performed to extract accurate ... more Quantum chemical calculations on embedded cluster models have been performed to extract accurate estimates of the magnetic coupling J and hopping parameters t of CaCu 2 O 3. It is shown that this copper oxide compound is best described as a quasi-one-dimensional spin chain with weak interchain interactions within and between the Cu 2 O 3 planes. This magnetic structure is not reflected in the hopping parameters, since we find a large interplane hopping. Hence, the use of the simple second-order expression that relates J, t, and the on-site repulsion U ͑J =−4t 2 / U͒ is not justified in all cases.
Physical Review Letters, Nov 22, 1993
Chemical Physics Letters, Apr 1, 1990
Physical Chemistry Chemical Physics, 2015
This work explores the electronic structure aspects involving the complete intermolecular O2 tran... more This work explores the electronic structure aspects involving the complete intermolecular O2 transfer between Ni (II) and Mn (II) complexes, both containing Ntetramethylated cyclams (TMC). The energy of the low-lying states of reactants, intermediates and products is established at the CASSCF level and also the DDCI level when possible. The orthogonal valence bond analysis of the wave functions obtained from CASSCF and DDCI calculations indicates the dominant superoxide nature of all the adducts participating in the reaction, and consequently that th whole reaction can be described as the transfer of the superoxide O2− between Ni (II) and Mn (II) complexes, without any additional change in the electronic structure of the fragments.
Journal of Computational Chemistry, Jan 15, 1996
ABSTRACT The relative stability of the 3A2, 1A2, and 1A1 states of phenylnitrene is evaluated by ... more ABSTRACT The relative stability of the 3A2, 1A2, and 1A1 states of phenylnitrene is evaluated by means of ab initio calculations followed by difference-dedicated configuration interaction (DDCI). This approach is based on effective Hamiltonian theory at a low order of perturbation to select rationally the determinants which contribute to the energy difference. The CI space built on this criterion is then treated variationally. The method allows a considerable reduction of the CI space compared with a complete CAS*SDCI calculation (where CAS stands for complete active space). Depending on the concerned energy difference, different model spaces may be chosen, as illustrated in the 3A2 → 1A2 and the 3A2 → 1A1 transitions in phenylnitrene. Since the CI space may reach considerable dimensions, a direct CI algorithm for selected CI spaces, the SCIEL algorithm, has been used to perform the calculations. The results are in excellent agreement with previous calculations and with available experimental data. © 1996 by John Wiley & Sons, Inc.
Journal de chimie physique, 1973
On construit les cartes conformationnelles de la glycine neutre et (le son zwitterion, au moyen d... more On construit les cartes conformationnelles de la glycine neutre et (le son zwitterion, au moyen de la méthode de Scheraga et de la méthode de Hückel étendue. De la comparaison des résultats, on déduit que les deux procédés fournissent une information semblable
Chemischer Informationsdienst, Nov 18, 1986
Physical Review Letters, Apr 18, 1994
ChemInform, Feb 7, 2014
ChemInform Abstract Die durch Kondensation von Pyridin-2-carbaldehyd, Salicylaldehyd oder Acetyla... more ChemInform Abstract Die durch Kondensation von Pyridin-2-carbaldehyd, Salicylaldehyd oder Acetylaceton mit den Diaminoalkanolen gebildeten Liganden reagieren mit Cu-Salzen in Gegenwart der Brücken-bildenden Pyrazolat-und Acetat-Ionen zu den Komplexen (I)-(IV). Pyrazol tauscht auch Einatombrücken in einigen Fällen aus, wie an der Darstellung der Komplexe (I) bzw. (IVa) durch Zugabe von Pyrazol zu den Hydroxo-bzw. Methoxo-verbrückten Komplexen demonstriert wird. Der Komplex (III) (n: 1, XAX: Pyrazolat) wird röntgenographisch (RG Pbcn; Z=8) charakterisiert. Er zeigt keine intermolekularen Wechselwirkungen zwischen benachbarten Einheiten; der intramolekulare Cu-Cu-Abstand beträgt 3.359å. Magnetische Suszeptibilitäten werden für alle Verbindungen im festen Zustand im Temp.-Bereich 4.2-3OO K gemessen. Ein Vergleich der magnetischen Daten dieser Zweiatom-Brücken-Spezies mit analogen Einatom-Brücken-Spezies zeigt, dass-J in der Reihe OR'-pyrazolat acetat a-OH' C1' sinkt (Ausb.-Angaben in g).
Journal of Computational Chemistry, Nov 4, 2010
Highlight To the best of our knowledge we present the first study on the relative interface ene... more Highlight To the best of our knowledge we present the first study on the relative interface energies of coherent and semi-coherent oxide/III-V semiconductor interfaces. The HfO2/GaAs(100) and HfO2/GaP(100) interfaces are investigated. The coherent and semicoherent interfaces represent the main interfacial structural building blocks, Ga-O-Ga bridges and As (P) dimers, respectively. We consider several qualitatively different interfaces based on different oxide types. We present first realistic defect gap state free models for the HfO2/III-V interfaces. Various coherent and semi-coherent interfaces are stable and have band gaps free of defect states in spite of the interfacial structural defects. Defect energetics is discussed. Interface thermodynamics is not responsible for the possible formation of the semi-coherent interfaces including As (P) dimers. The dimers have previously been taken responsible for the harmful Fermi level pinning. Kinetics via the layer by layer growth favors semi-coherent interfaces under the relevant relatively O-rich growth conditions. This is explained by the interface bonding and the electron counting rule (ECR). The same reasoning is used to explain, why ordered oxidized III-V substrates can be used to decrease the interface defect density by a factor of 40 (previously reported to HfO2/InAs).
Physical Review B, Jan 11, 2005
Quantum chemical calculations on embedded cluster models have been performed to extract accurate ... more Quantum chemical calculations on embedded cluster models have been performed to extract accurate estimates of the magnetic coupling J and hopping parameters t of CaCu 2 O 3. It is shown that this copper oxide compound is best described as a quasi-one-dimensional spin chain with weak interchain interactions within and between the Cu 2 O 3 planes. This magnetic structure is not reflected in the hopping parameters, since we find a large interplane hopping. Hence, the use of the simple second-order expression that relates J, t, and the on-site repulsion U ͑J =−4t 2 / U͒ is not justified in all cases.
Origins of Life, 1976
A theoretical methodology for the systematic study of the interstellar molecules is proposed. Som... more A theoretical methodology for the systematic study of the interstellar molecules is proposed. Some examples, dealing with formaldehyde excited states, formyl radical and ion, reactivity of the excited states of formic acid, methyl cyanide and methyl acetylene, as well as the reaction patho of formaldehyde photodecomposition are presented. Quantum chemical methods appear to be a powerful tool to study the structure and behaviour of molecules related with interstellar space and the Origin of Life.
Chemical Physics Letters, 2008
ABSTRACT The magnetic coupling in the manganese dimer has been investigated with multiconfigurati... more ABSTRACT The magnetic coupling in the manganese dimer has been investigated with multiconfigurational computational schemes. Whereas the perturbational approaches present severe deviations to the expected Heisenberg behaviour, variational techniques based on difference dedicated configuration interaction (DDCI) perfectly fit a Heisenberg spectrum corresponding to antiferromagnetic coupling. This shows that the study of weak magnetic coupling as in Mn(2) is at (or beyond) the limit of applicability of perturbational techniques. Potential energy curves are obtained for the six low-lying R states by adding the DDCI energy difference to the reference potential energy surface calculated with coupled cluster techniques for the monoconfigurational 11 Sigma(+)(g) g state. (c) 2008 Elsevier B.V. All rights reserved.
Journal of Chemical Physics, Jul 8, 1998
The iterative difference dedicated configuration interaction (IDDCI) method, recently proposed fo... more The iterative difference dedicated configuration interaction (IDDCI) method, recently proposed for calculating excited electronic states, is tested in systems where the core-valence correlation plays an important role. The calculated ionization potential, electron affinity, and electronic transition energies of K and Rb agree within 0.1 eV with experimental values. The three lowest Σ+ potential curves of KH and RbH and the six lowest states Σg+, Σu+, and Πu of K2 are calculated with the same accuracy.
Chemical Physics Letters, 1987
Ab initio calculations using pseudopotentials and configuration interaction (CI) are performed on... more Ab initio calculations using pseudopotentials and configuration interaction (CI) are performed on H3Y…HX (Y=P, As; X =Cl, Br) hydrogen-bonded complexes. Electron correlation plays an important role in determining the binding energy as well as the Y…H distance. The binding energies range from 2.64 to 1.43 kcal mol−1, from second- to third-row complexes.
Inorganic Chemistry, 1996
Ab initio DDCI2 (difference-dedicated configuration interaction) calculations are performed on th... more Ab initio DDCI2 (difference-dedicated configuration interaction) calculations are performed on the exchange coupling constant of the doubly-bridged Ni(II) complexes [Ni(en) 2 Cl] 2 2+ and [Ni(terpy)(N 3)] 2 2+ , which are modeled by substituting the external ligands with ammonia groups. The variational CI space is selected on the grounds of the effective Hamiltonian theory and includes all the second-order contributions to the difference between the lowest quintet, triplet, and singlet states. Both complexes are found to be ferromagnetic, with coupling constants of 1.8 and 21.1 cm-1 , in good agreement with the experiment. A transformation of the molecular orbitals is also proposed for large systems, enabling the molecular orbital set to be significantly truncatedsas well as the file of two-electron integrals and the DDCI2 spaceswith no loss of efficiency.
Journal de Chimie Physique, 1974
17 Espagne.) (Manuscrit reçu le 13.11.73.) SOMMAIRE L'analyse conformationnelle des éthylamines p... more 17 Espagne.) (Manuscrit reçu le 13.11.73.) SOMMAIRE L'analyse conformationnelle des éthylamines polychorées est effectuée au moyen de la méthode de Hückel étendue. On calcule les barrières de rotation concernant les deux degrés de rotation dans les amines et les ions correspondants. La méthode EH fournit un bon accord avec les résultats expé rimentaux, ainsi qu'avec les calculs « ah initio ».
Chemischer Informationsdienst, 1974
The Difference Dedicated Configuration Interaction method is described and its performance illust... more The Difference Dedicated Configuration Interaction method is described and its performance illustrated by applications on electronic transitions, singlettriplet separations and magnetic exchange coupling.
Physical Review B, 2005
Quantum chemical calculations on embedded cluster models have been performed to extract accurate ... more Quantum chemical calculations on embedded cluster models have been performed to extract accurate estimates of the magnetic coupling J and hopping parameters t of CaCu 2 O 3. It is shown that this copper oxide compound is best described as a quasi-one-dimensional spin chain with weak interchain interactions within and between the Cu 2 O 3 planes. This magnetic structure is not reflected in the hopping parameters, since we find a large interplane hopping. Hence, the use of the simple second-order expression that relates J, t, and the on-site repulsion U ͑J =−4t 2 / U͒ is not justified in all cases.