Multiple resonances in the semi-classical limit

We construct for the Schrödinger operator in the semi-classical limit compact perturbations of a radial symmetric potential which give rise to resonances associated to arbitrarily high order poles for the meromorphic extension of the resolvent. Our results concern the hamiltonianP ₀=–h ²–x ² in the 2-dimensional case, as well as a fairly large class of radial-symmetric potentials in the 3-dimensional case. We show that the poles of the resolvent for such a potential are necessarily simple, and subsequently the degeneracy is due to a lack of symmetry.     

Non-integer Slater orbital calculations

In order to calculate the one- and two-electron, two-center integrals over non-integer n Slater type orbitals, use is made of elliptical coordinates for the monoelectronic, hybrid, and Coulomb integrals. For the exchange integrals, the atomic orbitals are translated to a common center. The final integration is performed by Gaussian quadrature.As an example, an SCF ab initio calculation is performed for the LiH molecule, both with integer and non-integer principal quantum number.     

Quasicrystal Ising chain and automata theory

An automatic sequence is generated by a finite machine (automaton). These sequences can be periodic or not: in the latter case however, they are not random, but rather quasicrystalline. We consider an Ising chain with variable interaction in a uniform external field, at zero temperature, and prove that, if this interaction is automatic, then the induced magnetic field is also automatic.     

Intramolecular interactions in the triplet excited states of benzophenone-thymine dyads

Time-resolved and product studies on the synthesized dyads 1 and 2 have provided evidence that the benzophenone-to-thymine orientation strongly influences intramolecular photophysical and photochemical processes. The prevailing reaction mechanism has been established as a Paterno-Büchi cycloaddition to give oxetanes 3-6; however, the ability of benzophenone to achieve a formal hydrogen abstraction from the methyl group of thymidine has also been evidenced by the formation of photoproducts 7 and 8. These processes have been observed only in the case of the cisoid dyad 1. Adiabatic photochemical cycloreversion of the oxetane ring is achieved upon direct photolysis to give the starting dyad 1 in its excited triplet state. The photobiological implications of the above results are discussed with respect to benzophenone-photosensitized damage of thymidine.     

Synthesis of a New Cationic Pyropheophorbide Derivative and Studies of its Aggregation Process in Aqueous Solution

Abstract— A new water-soluble cationic pyropheophorbide was prepared from pyropheophorbide a by a Curtius rearrangement. The self-aggregation process of this chlorhydrate of aminopyropheophorbide was investigated from the changes observed in its spectroscopic properties when passing from ethanol to aqueous solutions. The formation of aggregates was characterized in the absorption spectrum by a broadening of the Qy band, which is slightly shifted to the red, a significant increase in signals of circular dichroism and a drastic quenching of the fluorescence intensity at 674 nm. Analysis of the nonlinear variation of the fluorescence intensity with the dye concentration in Tris-buffered solutions shows that dimerization is the dominant aggregation process. The dimerization equilibrium constant(at 25_AoC, pH 7.5 in 5 m M Tris buffer, 10 m M NaCl) was determined to be 3.10₆ M _-l. NMR measurements performed in DMSO at various dye concentrations showed that only the chemical shifts of some atoms are affected by these changes, indicating the part of the ring involved in the overlap of the two molecules in the dimer.A molecular modeling study of the packing arrangement of the aminopyropheophorbide molecules in aggregates performed by both semi-empirical quantum chemical PM3 and force field MM2 methods provided a structure consistent with these spectroscopic data.     

The influence of antiferroelectric compounds on helical pitch of orthoconic W-1000 mixture

The influence of six antiferroelectric compounds on the helical pitch of mixture W-1000, which was reported as long pitch orthoconic antiferroelectric liquid crystalline mixture, was checked by spectrophotometry and polarimetry methods. The electro-optical properties for the mixture with the longest pitch were measured. An improvement in electro-optical response due to the long pitch is reported. The novelty in electro-optical properties is the good symmetry response.     

Discrimination of metallosupramolecular architectures in solution by using diffusion ordered spectroscopy (DOSY) experiments: double-stranded helicates of different lengths

The translational diffusion coefficients of various helicates have been determined by using NMR diffusion spectroscopy (Diffusion Ordered SpectroscopY, DOSY), in order to investigate the individual behaviour of the helicates according to their length (different nuclearities; 1-5 metals), to the nature of the metal involved (CuI or AgI), as well to their bulkiness due to the presence of substituents on the periphery of the assembly. Furthermore, the spectrum of a mixture of helicates belonging to the same series, but with different lengths and nuclearities, showed the signals of each component, with no observable cross-linking, confirming the self-recognition properties of the helicates.     

Ab initio study of neutral and charged SinNap(+) (n <or= 6, p <or= 2) clusters

Ab initio calculations in the framework of the density functional theory, with B3LYP functional, are performed to study the lowest-energy isomers of silicon sodium clusters Si(n)Na(p)(+) (n 相似文献   

Structure of low-lying electronic states of NdO: quantum chemical calculations

Low-lying states of the NdO molecule have been predicted from quantum mechanical complete active-space self-consistent field/multireference configuration interaction/spin-orbit calculations. 54 states labeled through the quantum number Omega(+/-) have been determined in the excitation energy range of approximately 1 eV. For each state molecular constants T(e), T(v), omega(e), deltaG(v), R(e), B(e), and B(v) have been calculated. All these states display nearly identical principal structural characteristics: equilibrium internuclear distance and vibrational frequency. Calculated values of T(v), deltaG(v), and B(v) agree satisfactorily with experimental values available for nine electronic states among the 54 considered. The feasibility of a statistical representation of the low-lying states of NdO is considered.