Papers by Carlos Del Valle
Phys Rev a, 1994
In our theoretical studies with replacement operators, we found the use of a graphical method ver... more In our theoretical studies with replacement operators, we found the use of a graphical method very useful for operating with them. Now, for working with spin-orbital fermion operators, we have devised another easy graphical method which has proven to be very helpful to us. This method is presented here and as an example the square of the Hamiltonian operator is evaluated.
Journal of Molecular Structure Theochem, Nov 1, 1996
The energetics of the ionic dissociation of the hydroperoxyl radical (HOZ) into the H' and 0; ion... more The energetics of the ionic dissociation of the hydroperoxyl radical (HOZ) into the H' and 0; ions in solution is studied using ab initio methods and water clusters to mimic the solvent effects. The clusters selected are HO,..(H,O),, H'..(H@), and 0;..+(H20),, using various combinations of n, 1 and m designed to saturate the first solvation shell of the involved systems, the largest of which contains 10 water molecules (n = 10) plus the electrostatic field created by the outer solvation shell to these 10 water molecules. We have optimized the geometries of these clusters at the Hartree-Pock level using the 6-31 + + G(d,p) basis set. The impact of the electronic correlation, using the same basis set, was included using the second-order Moller-Plesset method and the Becke-Lee-Yang-Parr density functional, obtaining similar results from both methods. Our results indicate that in order to obtain reasonable values of the ionic dissociation energy, one has to use large clusters which saturate the first solvation shell of the HO2 molecule and that of the ionic products in an even way. The structures of the clusters are given and rationalized.
Signo Y Pensamiento, Jul 1, 2010
Revista Medica De Chile, Nov 21, 2011
Background: University students are especially vulnerable towards substance abuse Aim: To describ... more Background: University students are especially vulnerable towards substance abuse Aim: To describe and compare drug consumption in students of a Chilean university who attended first and fourth year of studies, according to gender and faculty. Material and ...
Eniac Pesquisa, Dec 31, 2014
Interamerican Journal of Psychology, Jan 30, 2013
Augusto Guzzo Revista Academica, Dec 26, 2014
Signo Y Pensamiento, Jul 1, 2010
Revista De Investigacion En Psicologia, 2011
In a highly complex social and cultural scenery, understanding of economics has turned out to be ... more In a highly complex social and cultural scenery, understanding of economics has turned out to be a basic need for social adaptation and the practice of citizenship. The present work is a review of the state of the art in research on the understanding of economics with special emphasis on Latin-American and national studies. It also questions the current role
Jornal Vascular Brasileiro
Background: Symptoms and clinical signs suggestive of deep vein thrombosis (DVT) are common but m... more Background: Symptoms and clinical signs suggestive of deep vein thrombosis (DVT) are common but may have numerous possible causes. Objectives: 1) To identify the most frequent clinical symptoms and correlate them with duplex ultrasound scan (DS) findings; 2) to identify high-risk clinical conditions for DVT; and 3) to evaluate time since the onset of symptoms and DS examination. Methods: A total of 528 patients with a clinical suspicion of DVT were evaluated by DS performed by experienced vascular ultrasonographists. Results: DVT was present in 192 (36.4%) of the patients. The external iliac vein was involved in 53 patients (10.04%), the femoral veins in 110 (20.83%), the popliteal vein in 124 (23.48%), and veins below the knee were involved in 157 (29.73%) of the cases. Limb swelling was present in 359 cases (68%), and 303 (57.4%) complained of pain. Sixty nine patients received a DS due to suspected or proven pulmonary embolism (PE); 79 patients were in postoperative period.
Proceedings of the National Academy of Sciences of the United States of America, Jan 20, 1999
The experimental and theoretical bases for a synchronous or concerted double-proton transfer in c... more The experimental and theoretical bases for a synchronous or concerted double-proton transfer in centro-symmetric H-bonded electronically excited molecular dimers are presented. The prototype model is the 7-azaindole dimer. New research offers confirmation of a concerted mechanism for excited-state biprotonic transfer. Recent femtosecond photoionization and coulombic explosion techniques have given rise to time-of-flight MS observations suggesting sequential two-step biprotonic transfer for the same dimer. We interpret the overall species observed in the time-of-flight experiments as explicable without conflict with the concerted mechanism of proton transfer.
Journal of Physical Chemistry a, 2008
Methylation at the 1N position of 2-phenylimidazole provides the shortest wavelength for a liquid... more Methylation at the 1N position of 2-phenylimidazole provides the shortest wavelength for a liquid-state laser dye reported to date; that is, the 1-methyl-2-phenylimidazole molecule in cyclohexane solution yields amplified spontaneous emission (ASE) with a peak wavelength at 314.5 nm and a constant laser gain value of 5 cm -1 from 310 to 317 nm. Methyl substitution in this case favors the appearance of laser action (owing to a torsion-vibrational mechanism) in cyclohexane as compared with the nonmethylated species which does not exhibit ASE in this solvent. The 2-(2′-hydroxyphenyl)imidazole molecules give rise to ASE with high gain values (ca. 9 cm -1 ) at 450 and 466 nm. The mechanism of population inversion is understood in terms of a vibronic coupling between the hydroxyl stretching motion and the torsional vibration of the phenyl and imidazole rings. The proton-transfer spectroscopy of 2-(2′-hydroxyphenyl)imidazoles is studied in dioxane, cyclohexane, dimethyl sulfoxide, methanol, and water. The greater the acidity of the solvent the greater the disruption of the intramolecular hydrogen bond; solvent acidity is the main parameter which favors formation of the open-form species in the ground electronic state. Methyl substitution at the 1N position favors formation of the open species for 2-hydroxyphenylimidazoles in the ground electronic state, which decreases their own capacity to undergo ASE. Low-temperature absorption spectroscopy confirms aggregation processes for 2-(2′hydroxyphenyl)imidazoles in solution. In accordance with X-ray analyses in the solid phase, these molecules form associations through intermolecular chains of the type NsH · · · O or OsH · · · N.
Journal of Molecular Structure: THEOCHEM, 2006
A key feature of the implementation of density-functional theory (DFT) in many quantum chemistry ... more A key feature of the implementation of density-functional theory (DFT) in many quantum chemistry programs is the use of a charge density fitting (CDF) or resolution-of-the-identity (RI) auxiliary basis. One of these, namely the present-day deMon2k (21st century version of densité de Montréal) program, makes particularly heavy use of the CDF algorithm. We report the first fully consistent implementation of time-dependent density-functional theory (TDDFT) response theory into the present-day deMon code, by which we mean both (i) that the static limit yields analytic derivatives which are correct for the numerical method adapted by deMon2k in solving the Kohn-Sham orbital equations and (ii) that the eigenvalue equation appearing in the Casida formulation of TDDFT is properly symmetric. The new implementation is also entirely consistent with using the charge conservation constraint (CCC) in the CDF algorithm. Example calculations on the sodium dimer and tetramer and on paraaminobenzonitrile are given showing that the effect of the CCC on TDDFT excitation energies is minor compared to the importance of choosing an adequate auxiliary basis set. q
The Journal of Physical Chemistry, 1994
The tautomeric equilibrium between 1H-and 2H-indazoles both in the ground (SO) and in the excited... more The tautomeric equilibrium between 1H-and 2H-indazoles both in the ground (SO) and in the excited state (S1) have been investigated by photophysical and thermochemical techniques, as well as by theoretical calculations. In the excited state indazole is 3.8 pKa ...
Revista médica de Chile, 2011
Background: University students are especially vulnerable towards substance abuse Aim: To describ... more Background: University students are especially vulnerable towards substance abuse Aim: To describe and compare drug consumption in students of a Chilean university who attended first and fourth year of studies, according to gender and faculty. Material and ...
Revista chilena de nutrición, 2013
Journal of Molecular Structure: THEOCHEM, 1996
The energetics of the ionic dissociation of the hydroperoxyl radical (HOZ) into the H' and 0; ion... more The energetics of the ionic dissociation of the hydroperoxyl radical (HOZ) into the H' and 0; ions in solution is studied using ab initio methods and water clusters to mimic the solvent effects. The clusters selected are HO,..(H,O),, H'..(H@), and 0;..+(H20),, using various combinations of n, 1 and m designed to saturate the first solvation shell of the involved systems, the largest of which contains 10 water molecules (n = 10) plus the electrostatic field created by the outer solvation shell to these 10 water molecules. We have optimized the geometries of these clusters at the Hartree-Pock level using the 6-31 + + G(d,p) basis set. The impact of the electronic correlation, using the same basis set, was included using the second-order Moller-Plesset method and the Becke-Lee-Yang-Parr density functional, obtaining similar results from both methods. Our results indicate that in order to obtain reasonable values of the ionic dissociation energy, one has to use large clusters which saturate the first solvation shell of the HO2 molecule and that of the ionic products in an even way. The structures of the clusters are given and rationalized.
Estudios pedagógicos (Valdivia), 2014
Revista de Psicología, 2012
En un escenario social y cultural altamente complejo, la comprensión de la economía se ha convert... more En un escenario social y cultural altamente complejo, la comprensión de la economía se ha convertido en una necesidad básica de adaptación social y de ejercicio de ciudadanía. En este trabajo se analiza el estado del arte en la investigación de la comprensión de la economía, con especial énfasis en los estudios latinoamericanos y nacionales. Se cuestiona también el papel actual de la educación en la implementación de una adecuada alfabetización económica en la escuela, presentando el programa "Yo y la economía" como una respuesta desde la psicología educacional a los temas claves para la educación económica. Palabras clave: Alfabetización económica, desarrollo del pensamiento económico, educación económica.
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Papers by Carlos Del Valle