Accurate ab initio Quartic Force Fields of Cyclic and Bent HC2N Isomers

Highly correlated ab initio quartic force field (QFFs) are used to calculate the equilibrium structures and predict the spectroscopic parameters of three HC2N isomers. Specifically, the ground state quasilinear triplet and the lowest cyclic and bent singlet isomers are included in the present study. Extensive treatment of correlation effects were included using the singles and doubles coupled-cluster method that includes a perturbational estimate of the effects of connected triple excitations, denoted CCSD(T). Dunning s correlation-consistent basis sets cc-pVXZ, X=3,4,5, were used, and a three-point formula for extrapolation to the one-particle basis set limit was used. Core-correlation and scalar relativistic corrections were also included to yield highly accurate QFFs. The QFFs were used together with second-order perturbation theory (with proper treatment of Fermi resonances) and variational methods to solve the nuclear Schr dinger equation. The quasilinear nature of the triplet isomer is problematic, and it is concluded that a QFF is not adequate to describe properly all of the fundamental vibrational frequencies and spectroscopic constants (though some constants not dependent on the bending motion are well reproduced by perturbation theory). On the other hand, this procedure (a QFF together with either perturbation theory or variational methods) leads to highly accurate fundamental vibrational frequencies and spectroscopic constants for the cyclic and bent singlet isomers of HC2N. All three isomers possess significant dipole moments, 3.05D, 3.06D, and 1.71D, for the quasilinear triplet, the cyclic singlet, and the bent singlet isomers, respectively. It is concluded that the spectroscopic constants determined for the cyclic and bent singlet isomers are the most accurate available, and it is hoped that these will be useful in the interpretation of high-resolution astronomical observations or laboratory experiments

Rovibrational Spectroscopic Constants and Fundamental Vibrational Frequencies for Isotopologues of Cyclic and Bent Singlet HC2N isomers

Through established, highly-accurate ab initio quartic force fields (QFFs), a complete set of fundamental vibrational frequencies, rotational constants, and rovibrational coupling and centrifugal distortion constants have been determined for both the cyclic 1(sup 1) 1A' and bent 2(sup 1)A' DCCN, H(C13)CCN, HC(C-13)N, and HCC(N-15) isotopologues of HCCN. Spectroscopic constants are computed for all isotopologues using second-order vibrational perturbation theory (VPT2), and the fundamental vibrational frequencies are computed with VPT2 and vibrational configuration interaction (VCI) theory. Agreement between VPT2 and VCI results is quite good with the fundamental vibrational frequencies of the bent isomer isotopologues in accord to within a 0.1 to 3.2 / cm range. Similar accuracies are present for the cyclic isomer isotopologues. The data generated here serve as a reference for astronomical observations of these closed-shell, highly-dipolar molecules using new, high-resolution telescopes and as reference for laboratory studies where isotopic labeling may lead to elucidation of the formation mechanism for the known interstellar molecule: X 3A0 HCCN

Rotational spectroscopic characterisation of the [D2,C,S] system: an update from the laboratory and theory

The synergy between high-resolution rotational spectroscopy and quantum-chemical calculations is essential for exploring future detection of molecules, especially when spectroscopy parameters are not available yet. By using highly correlated ab initio quartic force fields (QFFs) from explicitly correlated coupled cluster theory, a complete set of rotational constants and centrifugal distortion constants for D$_2$CS and cis/trans-DCSD isomers have been produced. Comparing our new ab initio results for D$_2$CS with new rotational spectroscopy laboratory data for the same species, the accuracy of the computed B and C rotational constants is within 0.1% while the A constant is only slightly higher. Additionally, quantum chemical vibrational frequencies are also provided, and these spectral reference data and new experimental rotational lines will provide additional references for potential observation of these deuterated sulfur species with either ground-based radio telescopes or space-based infrared observatories.Comment: 15 pages, 2 figures and 1 appendix table; published in Molecular Physics (Tim Lee Memorial Issue

Desarrollo del vínculo terapéutico de niñas y niños con antecedentes de vulneración y el equipo de trabajo de la residencia colaboradora del SENAME del hogar Padre Alfonso Boess

Tesis (Terapia Ocupacional)La siguiente investigación se desarrolla en base a las condiciones de vulneración de derechos por las que atraviesan millones de niños, niñas y adolescentes en Chile; a partir de esto surge la problemática sobre cómo esta vulneración influye sobre los procesos de vinculación de niños y niñas, que además se encuentran en una situación de protección, residiendo en hogares que se encuentran bajo el alero de una institución como SENAME. Además, a pesar de no limitarse al desempeño de la disciplina, esta será abordada desde un enfoque y perspectiva de Terapia Ocupacional, tomando en consideración factores y conceptos que se utilizan principalmente desde el área.The next research is developed based on the conditions of vulnerability of rights that millions of children and teenagers of Chile go through, because of this is that the problematic of how this vulnerability affects over the process of bond of children emerges that they also are in a situation of protection, living in juvenile welfare’s that are represented by an institution like SENAME. Also, despite of not limiting discipline performance, it will be approached by a Occupational Therapy focus and perspective, taking in consideration facts and concepts that are primarily used by that area

Carbon-Chain Molecules in Molecular Outflows and Lupus I Region--New Producing Region and New Forming Mechanism

Using the new equipment of the Shanghai Tian Ma Radio Telescope, we have searched for carbon-chain molecules (CCMs) towards five outflow sources and six Lupus I starless dust cores, including one region known to be characterized by warm carbon-chain chemistry (WCCC), Lupus I-1 (IRAS 15398-3359), and one TMC-1 like cloud, Lupus I-6 (Lupus-1A). Lines of HC3N J=2-1, HC5N J=6-5, HC7N J=14-13, 15-14, 16-15 and C3S J=3-2 were detected in all the targets except in the outflow source L1660 and the starless dust core Lupus I-3/4. The column densities of nitrogen-bearing species range from 10$^{12}$ to 10$^{14}$ cm$^{-2}$ and those of C$_3$S are about 10$^{12}$ cm$^{-2}$. Two outflow sources, I20582+7724 and L1221, could be identified as new carbon-chain--producing regions. Four of the Lupus I dust cores are newly identified as early quiescent and dark carbon-chain--producing regions similar to Lup I-6, which together with the WCCC source, Lup I-1, indicate that carbon-chain-producing regions are popular in Lupus I which can be regard as a Taurus like molecular cloud complex in our Galaxy. The column densities of C3S are larger than those of HC7N in the three outflow sources I20582, L1221 and L1251A. Shocked carbon-chain chemistry (SCCC) is proposed to explain the abnormal high abundances of C3S compared with those of nitrogen-bearing CCMs. Gas-grain chemical models support the idea that shocks can fuel the environment of those sources with enough $S^+$ thus driving the generation of S-bearing CCMs.Comment: 7 figures, 8 tables, accepted by MNRA

Consumidor de la región del Maule sin experiencia en el comercio digital: Covid19 y el paso obligado de la compra offline a online

279 p.Producto de la crisis sanitaria el consumidor chileno se ha visto en la obligación de comprar de manera online. Esta obligación, junto al aislamiento social ha provocado en los consumidores distintos sentimientos negativos. Si bien existen diferentes estudios empíricos sobre el consumidor chileno, estos no explican en profundidad cómo vivió el cambio de la compra offline a online el consumidor de la región del Maule. Buscando entender mejor este fenómeno, se realizó un análisis temático de Braun y Clarke (2006) que consta de seis fases donde se genera un mapa temático con los temas centrales que responden la pregunta de investigación. Se aplicaron 18 entrevistas a profundidad a ciudadanos de la región del Maule con el fin de conocer su experiencia en el paso de la compra presencial a la compra virtual. Se obtuvieron cinco temáticas principales que resumen la experiencia del consumidor. La primera se relaciona la pandemia como un limitante para las compras presenciales. La segunda tiene relación con las características de cada consumidor y como estas dificultaron la adopción de la compra online. El tercer tema tiene relación con los desafíos que afrontaron los consumidores para comprar online. El cuarto tema tiene relación con los incentivos que encontraron los consumidores para comprar online. El quinto y último tema está relacionado con la evaluación final sobre la compra online y la decisión de continuidad en el futuro que tomaron los consumidores. Gracias a estos temas, se puede concluir que el consumidor inició sus compras online por obligación debido a las restricciones por la pandemia. Posteriormente, a través de ayuda de terceros y las ventajas de la compra online, el consumidor logró utilizar la plataforma y comenzó a ver desventajas en la compra presencial. Finalmente, el consumidor evalúa la compra online en base a sus sentimientos y experiencias toma la decisión de continuar o no en este canal de compra. Esto es útil para las empresas que quieran mejorar la experiencia de compra online en los consumidores. // ABSTRACT: Due to health crisis, the Chilean consumer has been forced to buy online. This obligation, together with social isolation, has caused different negative feelings in consumers. Although there are different empirical studies on the Chilean consumer, they do not explain in depth how the consumer in the Maule region experienced the change from offline to online shopping. Seeking to better understand this phenomenon, a thematic analysis by Braun and Clarke (2006) was carried out, which consists of six phases where a thematic map is generated with the central themes that answer the research question. 18 in-depth interviews were applied to citizens of the Maule region in order to learn about their experience in the transition from face-to-face to virtual purchase. Five main themes were obtained that summarize the consumer experience. The first relates to the pandemic as a limitation for face-to-face purchases. The second is related to the characteristics of each consumer and how these hindered the adoption of online shopping. The third theme is related to the challenges faced by consumers to buy online. The fourth theme is related to the incentives that consumers found to buy online. The fifth and last topic is related to the final evaluation of online shopping and the decision to continue in the future made by consumers. Thanks to these topics, it can be concluded that the consumer started their purchases in e-Retail due to the obligation due to the restrictions due to the pandemic. Later, through the help of third parties and the advantages of online shopping, the consumer was able to use the platform and began to see disadvantages in the face-to-face purchase. Finally, the consumer evaluates the online purchase based on his feelings and experiences and makes the decision to continue or not in this purchase channel. This is useful for companies that want to improve the online shopping experience for consumers

Estudio teórico del espectro ro-vibracional en moléculas interestelares

Tesis (Doctor en Fisicoquímica Molecular)En esta tesis Doctoral se presenta el estudio teórico del espectro ro-vibracional en moléculas con interés astrofísico. Muchas de las especies detectadas en el medio interestelar corresponden a radicales, iones y compuestos orgánicos altamente insaturados. Estas en su mayoría son inestables y difíciles de tratar a nivel laboratorio. Considerando estas características, sus propiedades electrónicas se obtienen de la aplicación de métodos ab initio de alto nivel que incluyen los efectos de la correlación electrónica. El objetivo principal de este trabajo es contribuir con un espectro ro-vibracional teórico, que permita la interpretación de las medidas observacionales. El estudio se ha realizado en moléculas detectadas en el medio interestelar 12CF+, 28Si0, 29Si0, 30Si0, así como, en moléculas potencialmente detectables, como el ión molecular 28SiF+ y sus respectivos isótopos 29SiF+, 30SiF+ además de los isómeros lineales 1-SiCCC y 1-CSiCC. Para la determinación de propiedades espectroscópicas, el trabajo abarcó aproximaciones más allá del límite dado por los cálculos ab initio. Los métodos desarrollados y aplicados, nos permiten incluir correcciones de anarmonicidad, distorsión centrífuga y acoplamientos ro-vibracionales, todas correcciones importantes a la hora de contrastar valores experimentales con datos teóricos. Los principales resultados en moléculas diatómicas muestran una diferencia promedio de ±0.1 cm -1 entre las transiciones ro-vibracionales calculadas en este trabajo y las medidas observacionales. Se determina para el caso de los isómeros lineales 1-SiCCC y 1-CSiCC que es imprescindible la utilización de métodos multideterminantales. Por otro lado, analizando los resultados derivados de la descripción espectroscópica y electrónica que incluyen excitaciones verticales y acoplamiento espín-orbita, se concluye que el isómero 1-SiCCC es un potencial candidato al centro de banda ubicado a 174 cm-1 en la estrella rica en carbono IRC+10216.The theoretical study of the ro-vibrational spectra of molecules of astrophysical interest is presented. Many of the species detected in the interstellar medium are radicals, ions and highly unsaturated organic compounds. These are mostly unstable and hard to handle in the laboratory. Owing to these characteristics, their electronic properties are obtained through high-level ab initio methods that take into account electronic correlation. The main goal in this work is to contribute with theoretical ro-vibrational spectra that allow interpretation of experimental observations. This study is concerned with the following molecules, already detected in the interstellar medium (IM) 12CF+, 28Si0, 29Si0, 30Si0, as well as other potentially detectable molecules, such as the molecular ion 28SiF+ and their respectives isotopomors 29SiF+, 30SiF+ and in addition the linear isomers 1-SiCCC y 1-CSiCC. For the determination of spectroscopic properties one needs to use approximations beyond the limit of the ab initio calculations. The methods developed here allow including anharmonicity corrections, centrifuga! distortion and ro-vibrational coupling. All of them are important when contrasting theoretical results with experimental values. The main results in diatomic molecules show an average difference of ± 0.1 cm- 1 between ro-vibrational transitions calculated in this work and observational measures. For the case of 1-SiCCC and 1-CSiCC linear isomers is determined that it is essential to use multideterminant methods. Furthermore, analyzing the results derived from spectroscopic and electronic description including vertical excitations and spin-orbit coupling, we conclude that the fundamental frequency of the 1-SiCCC isomer is a potential candidate for the band center located at 17 4 cm-1 in the carbon rich star IRC +10216

Methanediol CH

Context. Ab initio molecular dynamics simulations were carried out to study the formation pathways to complex organic molecules when a OH+ projectile hit an interstellar dust grain covered only by methanol molecules. The selected target material is a methanol cluster formed by ten units (CH3OH)10. Aims. The focus of this paper is the process where methanediol CH2(OH)2 and hydroxymethyl CH2OH+, both key organic intermediate molecules, were involved in the formation mechanisms of stable complex organic molecules (COMs). Methods. We performed Born-Oppenheimer (ab initio) molecular dynamics (BOMD) simulations under the hybrid functional of Head-Gordon ωB97X-D. We used the initial kinetic impact energy of 10, 12, 15, 18, 20, and 22 eV. Results. We corroborate that CH2(OH)2 and CH2OH+ are the main precursors to form molecules such as methoxymethanol CH3OCH2OH, the formyl radical HCO, the Criegee biradical CH2OO, and formaldehyde H2Co and its elusive HCOH isomer. We discuss the mechanism formation of these complex organic molecules. We compare the formation pathways with previous theoretical results where both key intermediates are present. The pathways in some cases go through CH2(OH)2 or undergo by CH2OH+. Conclusions. We confirm that CH2(OH)2 and CH2OH+ play a key role on the path to the formation of abundant H2CO. These mechanisms can give insight into alternative pathways relevant to understanding experimental processes with key steps within those precursors