2D-Delocalized vs Confined Diradicals

Resumen de la comunicación oral seleccionadaDiradicals are beautiful chemical objects where the more basic and intricate aspects of the chemical bonding are revealed.1 Not this being important enough, nowadays, diradical-based substrates are becoming very appealing for new organic electronic applications. We focus here in conjugated organic diradicals formed by competition between non-aromatic quinoidal structures and their canonical aromatic forms. How this quinoidal(closed-shell)-vs-aromatic(open-shell) energetic balance producing the diradical is affected by several situations has been our objective in the last few years.2 Now, we focusses on how the properties of diradicals are influenced when several diradical canonical forms are available in such a way that create a 2D (i.e., bidimensional) electron delocalization surface in which the diradical substructures are in cross-conjugation mode producing the curious effect of diradical confinement.3 Herein, the diradical molecular properties of compound 1 in Figure 1 will be discussed in connection with 2D delocalization, cross-conjugation and surface confinement. 1. Rajca, A., Chem. Rev., 1994, 94, 871; Abe, M., Chem. Rev. 2013, 113, 7011. 2. Zeng, Z.; X. Shi, L.; Chi, C.; Casado, J.; Wu, J. Chem. Soc. Rev. 2015, 44, 6578. 3. Yuan, D.; Huang, D.; Medina Rivero, S.; Carreras, A.; Zhang, C.; Zou, Y.; Jiao, X.; McNeill, C.R.; Zhu, X.; Di, C.; Zhu, D.; Casanova, D.; Casado, J. CHEM, 2019, accepted.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Exact solution for a two-phase Stefan problem with variable latent heat and a convective boundary condition at the fixed face

Recently it was obtained in [Tarzia, Thermal Sci. 21A (2017) 1-11] for the classical two-phase Lam\'e-Clapeyron-Stefan problem an equivalence between the temperature and convective boundary conditions at the fixed face under a certain restriction. Motivated by this article we study the two-phase Stefan problem for a semi-infinite material with a latent heat defined as a power function of the position and a convective boundary condition at the fixed face. An exact solution is constructed using Kummer functions in case that an inequality for the convective transfer coefficient is satisfied generalizing recent works for the corresponding one-phase free boundary problem. We also consider the limit to our problem when that coefficient goes to infinity obtaining a new free boundary problem, which has been recently studied in [Zhou-Shi-Zhou, J. Engng. Math. (2017) DOI 10.1007/s10665-017-9921-y].Comment: 16 pages, 0 figures. arXiv admin note: text overlap with arXiv:1610.0933

Comment on "Geometric phases for mixed states during cyclic evolutions"

It is shown that a recently suggested concept of mixed state geometric phase in cyclic evolutions [2004 {\it J. Phys. A} {\bf 37} 3699] is gauge dependent.Comment: Comment to the paper L.-B. Fu and J.-L. Chen, J. Phys. A 37, 3699 (2004); small changes; journal reference adde

Number of states for nucleons in a single-jj shell

In this paper we obtain number of states with a given spin $I$ and a given isospin $T$ for systems with three and four nucleons in a single-$j$ orbit, by using sum rules of six-$j$ and nine-$j$ symbols obtained in earlier works.Comment: to be published in Physical Review

Spin-1 charmonium-like states in QCD sum rule

We study the possible spin-1 charmonium-like states by using QCD sum rule approach. We calculate the two-point correlation functions for all the local form tetraquark interpolating currents with $J^{PC}=1^{--}, 1^{-+}, 1^{++}$ and $1^{+-}$ and extract the masses of the tetraquark charmonium-like states. The mass of the $1^{--}$ $qc\bar q\bar c$ state is $4.6\sim4.7$ GeV, which implies a possible tetraquark interpretation for Y(4660) meson. The masses for both the $1^{++}$ $qc\bar q\bar c$ and $sc\bar s\bar c$ states are $4.0\sim 4.2$ GeV, which is slightly above the mass of X(3872). For the $1^{-+}$ and $1^{+-}$ $qc\bar q\bar c$ states, the extracted masses are $4.5\sim4.7$ GeV and $4.0\sim 4.2$ GeV respectively.Comment: 7 pages, 2 figures. arXiv admin note: substantial text overlap with arXiv:1010.339