Jesús González-Vázquez

Bio: Jesús González-Vázquez is an academic researcher from Autonomous University of Madrid. The author has contributed to research in topics: Excited state & Ionization. The author has an hindex of 22, co-authored 90 publications receiving 1926 citations. Previous affiliations of Jesús González-Vázquez include Free University of Berlin & Spanish National Research Council.

SHARC: ab Initio Molecular Dynamics with Surface Hopping in the Adiabatic Representation Including Arbitrary Couplings

Abstract: We present a semiclassical surface-hopping method which is able to treat arbitrary couplings in molecular systems including all degrees of freedom. A reformulation of the standard surface-hopping scheme in terms of a unitary transformation matrix allows for the description of interactions like spin−orbit coupling or transitions induced by laser fields. The accuracy of our method is demonstrated in two systems. The first one, consisting of two model electronic states, validates the semiclassical approach in the presence of an electric field. In the second one, the dynamics in the IBr molecule in the presence of spin−orbit coupling after laser excitation is investigated. Due to an avoided crossing that originates from spin−orbit coupling, IBr dissociates into two channels: I + Br(2P3/2) and I + Br*(2P1/2). In both systems, the obtained results are in very good agreement with those calculated from exact quantum dynamical simulations.

Femtosecond Intersystem Crossing in the DNA Nucleobase Cytosine.

Abstract: Ab initio molecular dynamics including nonadiabatic and spin–orbit couplings on equal footing is used to unravel the deactivation of cytosine after UV light absorption. Intersystem crossing (ISC) is found to compete directly with internal conversion in tens of femtoseconds, thus making cytosine the organic compound with the fastest triplet population calculated so far. It is found that close degeneracy between singlet and triplet states can more than compensate for very small spin–orbit couplings, leading to efficient ISC. The femtosecond nature of the ISC process highlights its importance in photochemistry and challenges the conventional view that large singlet–triplet couplings are required for an efficient population flow into triplet states. These findings are important to understand DNA photostability and the photochemistry and dynamics of organic molecules in general.

Control of ultrafast molecular photodissociation by laser-field-induced potentials

Abstract: Shaping potential energy surfaces by tailored strong laser pulses has now been shown to be a powerful method for controlling product yields in an ultrafast polyatomic photodissociation reaction. Control over the velocity of the product fragments is also achieved through the generation of light-induced conical intersections and modulating the potentials around them.

A detailed experimental and theoretical study of the femtosecond A-band photodissociation of CH(3)I.

Abstract: The real time photodissociation dynamics of CH(3)I from the A band has been studied experimentally and theoretically. Femtosecond pump-probe experiments in combination with velocity map imaging have been carried out to measure the reaction times (clocking) of the different (nonadiabatic) channels of this photodissociation reaction yielding ground and spin-orbit excited states of the I fragment and vibrationless and vibrationally excited (symmetric stretch and umbrella modes) CH(3) fragments. The measured reaction times have been rationalized by means of a wave packet calculation on the available ab initio potential energy surfaces for the system using a reduced dimensionality model. A 40 fs delay time has been found experimentally between the channels yielding vibrationless CH(3)(nu=0) and I((2)P(32)) and I(*)((2)P(12)) that is well reproduced by the calculations. However, the observed reduction in delay time between the I and I(*) channels when the CH(3) fragment appears with one or two quanta of vibrational excitation in the umbrella mode is not well accounted for by the theoretical model.

Singlet and triplet excited-state dynamics study of the keto and enol tautomers of cytosine.

Abstract: The photoinduced excited-state dynamics of the keto and enol forms of cytosine have been investigated by using ab initio surface-hopping to gain an understanding of the outcome of molecular beam femtosecond pump-probe photoionisation spectroscopy experiments. Both singlet and triplet states were included in the dynamics. The results show that triplet states play a significant role in the relaxation of the keto tautomer, whereas they are less important in the enol tautomer. In both forms, the T1 state minimum was found to be too low in energy to be detected in standard photoionisation spectroscopy experiments and therefore experimental decay times should arise from simultaneous relaxation to the ground state and additional intersystem crossing followed by internal conversion to the T1 state. In agreement with available experimental lifetimes, we observed three decay constants of 7, 270 and 1900 fs, the first two coming from the keto tautomer and the third from the enol form. Deactivation of the enol tautomer is due to internal conversion to the ground state through two ethylenic-type S1/S0 conical intersections.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

Ab initio calculation of vibrational absorption and circular dichroism spectra using density functional force fields

Abstract: : The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg

Molcas 8: New capabilities for multiconfigurational quantum chemical calculations across the periodic table.

Abstract: In this report, we summarize and describe the recent unique updates and additions to the Molcas quantum chemistry program suite as contained in release version 8. These updates include natural and spin orbitals for studies of magnetic properties, local and linear scaling methods for the Douglas-Kroll-Hess transformation, the generalized active space concept in MCSCF methods, a combination of multiconfigurational wave functions with density functional theory in the MC-PDFT method, additional methods for computation of magnetic properties, methods for diabatization, analytical gradients of state average complete active space SCF in association with density fitting, methods for constrained fragment optimization, large-scale parallel multireference configuration interaction including analytic gradients via the interface to the Columbus package, and approximations of the CASPT2 method to be used for computations of large systems. In addition, the report includes the description of a computational machinery for nonlinear optical spectroscopy through an interface to the QM/MM package Cobramm. Further, a module to run molecular dynamics simulations is added, two surface hopping algorithms are included to enable nonadiabatic calculations, and the DQ method for diabatization is added. Finally, we report on the subject of improvements with respects to alternative file options and parallelization.

Exploitation of Intrinsic Microporosity in Polymer-Based Materials

Abstract: The past decade has seen the development of microporous materials (i.e., materials containing pores of dimensions <2 nm) derived wholly from organic components. Here we review this nascent area with a particular emphasis on amorphous polymers that possess intrinsic microporosity (IM), which is defined as microporosity that arises directly from the shape and rigidity of component macromolecules. Although IM can be readily identified within soluble non-network polymers and oligomers, for network polymers it is harder to differentiate IM from template effects that are responsible for the microporosity within hyper-cross-linked networks. The numerous examples of microporous polymers assembled from rigid monomers by the formation of rigid linking groups are surveyed and their IM assessed. The potential applications of these materials are highlighted.