Serveis Tècnics de Recerca: Unitat de Ressonància Magnètica Nuclear

Resum de les principals funcions que realitza la Unitat de Ressonànica Magnètica Nuclear de la UdG

Simple finite field nuclear relaxation method for calculating vibrational contribution to degenerate four-wave mixing

A simple extended finite field nuclear relaxation procedure for calculating vibrational contributions to degenerate four-wave mixing (also known as the intensity-dependent refractive index) is presented. As a by-product one also obtains the static vibrationally averaged linear polarizability, as well as the first and second hyperpolarizability. The methodology is validated by illustrative calculations on the water molecule. Further possible extensions are suggested

A systematic and feasible method for computing nuclear contributions to electrical properties of polyatomic molecules

An analytic method to evaluate nuclear contributions to electrical properties of polyatomic molecules is presented. Such contributions control changes induced by an electric field on equilibrium geometry (nuclear relaxation contribution) and vibrational motion (vibrational contribution) of a molecular system. Expressions to compute the nuclear contributions have been derived from a power series expansion of the potential energy. These contributions to the electrical properties are given in terms of energy derivatives with respect to normal coordinates, electric field intensity or both. Only one calculation of such derivatives at the field-free equilibrium geometry is required. To show the useful efficiency of the analytical evaluation of electrical properties (the so-called AEEP method), results for calculations on water and pyridine at the SCF/TZ2P and the MP2/TZ2P levels of theory are reported. The results obtained are compared with previous theoretical calculations and with experimental values

Nuclear relaxation contribution to static and dynamic (infinite frequency approximation) nonlinear optical properties by means of electrical property expansions: Application to HF, CH4, CF4, and SF6

Electrical property derivative expressions are presented for the nuclear relaxation contribution to static and dynamic (infinite frequency approximation) nonlinear optical properties. For CF4 and SF6, as opposed to HF and CH4, a term that is quadratic in the vibrational anharmonicity (and not previously evaluated for any molecule) makes an important contribution to the static second vibrational hyperpolarizability of CF4 and SF6. A comparison between calculated and experimental values for the difference between the (anisotropic) Kerr effect and electric field induced second-harmonic generation shows that, at the Hartree-Fock level, the nuclear relaxation/infinite frequency approximation gives the correct trend (in the series CH4, CF4, SF6) but is of the order of 50% too small

Nuclear magnetic resonance chemical shifts with the statistical average of orbital-dependent model potentials in Kohn-Sham density functional theory

The performance of the SAOP potential for the calculation of NMR chemical shifts was evaluated. SAOP results show considerable improvement with respect to previous potentials, like VWN or BP86, at least for the carbon, nitrogen, oxygen, and fluorine chemical shifts. Furthermore, a few NMR calculations carried out on third period atoms (S, P, and Cl) improved when using the SAOP potential

Relations among several nuclear and electronic density functional reactivity indexes

A set of connections among several nuclear and electronic indexes of reactivity in the framework of the conceptual Density Functional Theory by using an expansion ofthe energy functional in terms of the total number of electrons and the normal coordinates within a canonical ensemble was derived. The relations obtained provided explicit links between important quantities related to the chemical reactivity of a system. This paper particularly demonstrates that the derivative of the electronic energy with respect to the external potential of a system in its equilibrium geometry was equal to the negative of the nuclear repulsion derivative with respect to the external potential

La responsabilidad contractual de los organizadores y los detallistas de viajes combinados

Con la entrada en vigor de la Ley 21/1995, de 6 de julio, reguladora de los viajes combinados (LVC) se instaura una nuevo régimen de responsabilidad contractual del organizador y el detallista. Ahora el consumidor de esos viajes no sólo mantiene una relación contractual con el organizador si no también, en su caso, el detallista, cuya actuación deja de tener carácter representativo. Ambos sujetos responderán frente al consumidor "en función de las obligaciones que les correspondan por su ámbito respectivo de gestión del viaje combinado..." (art. 11.1), circunstancia que plantea algunas dificultades en orden a delimitar el alcance de su responsabilidad. Esa misma norma establece la responsabilidad del organizador por los actos de los prestadores de los servicios del viaje utilizados como auxiliares en el cumplimiento contractual. Analizados los sujetos responsables, la presente tesis doctoral estudia los supuestos de incumplimiento del contrato de viaje, las partidas de daños resarcibles y su extensión. El trabajo propone distintos criterios en orden a calcular el valor de los daños por lesión al llamado interés de prestación, los daños corporales, los daños ocasionados por el extravío, destrucción o deterioro de objetos del consumidor, los daños por gastos inútiles y costes de negocios de reemplazo, los daños no patrimoniales y los daños por ganancias dejadas de obtener. Cada una de esas partidas e daños merece un estudio pormenorizado. Así, por ejemplo, se constatan enormes problemas en cuanto a la identificación e indemnización separada de los daños por frustración o pérdida de vacaciones, así como la nesesidad de establecer unas circunstancias a las que los jueces deban acogerse para llevar a cabo su valoración discrecional. La tesis propone que dichas circunstanciasd sean el alcance del incumplimiento del contrato de viaje, las condiciones personales del consumidor, el tipo de vacaciones objeto del viaje contratado y el valor residual de las vacaciones.