A supermolecular approach combined with an iterative electrostatic scheme was employed to investigate the nonlinear optical properties of the hybrid L-arginine phosphate monohydrate crystal, the procedure being aided by DFT calculations. The supermolecular scheme basically treated the molecules surrounding the unit cell as point charges; this approximation results in rapid convergence, making it a feasible method. DFT functionals of different flavors were considered: B3LYP, B2PLYP, CAM-B3LYP, ωB97, and M06HF, utilizing the 6-311 + G(d) basis set. All functionals gave sufficiently accurate values for the dipole moment (μ) with respect to the experimental value 32(2) D. For the average linear polarizability ([Formula: see text]) and the total first hyperpolarizability (β ), good agreement was observed between the DFT-calculated values and MP2-derived results reported in the literature. For the second hyperpolarizability, both static and dynamic regimes were considered. The point-charge embedding approach led to an attenuation of the second hyperpolarizability γ for all frequencies considered. Excitations of γ were not observed for frequencies smaller than 0.1 a.u. For the second hyperpolarizability (both static and dynamic), computational results showed that L-arginine phosphate monohydrate exhibits a large nonlinear optical effect, which implies the occurrence of microscopic third-order NLO behavior.
In this work we determine the linear and non-linear optical properties of a Fluoro-N-Acylhydrazide derivative (FBHZ), using a combined supermolecule approach and an iterative scheme of electrostatic polarization, where the atoms of neighbouring molecules are represented by point charges. Our results for non-linear optics (NLO) are comparable to those found experimentally, suggesting that FBHZ constitutes an attractive object for future studies and for use as an interesting material for third-order NLO applications. The dynamic electrical properties of FBHZ in different solvent media are reported. Its molecular properties are closely related to supramolecular features; accordingly, we analysed all its crystal structure properties via intermolecular interactions in the solid state, using X-ray crystallography data and Hirshfeld surface (HS), including thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and hot-stage microscopy (HSM), where the results reveal crystal stability in respect to temperature variation.
A fim de diversificar a utilização dos aços comuns nas indústrias, é preciso que sua estrutura cristalina seja modificada, para tanto, são realizados tratamentos térmicos e termoquímicos. Para realização desses tratamentos, são considerados os seguintes fatores: aquecimento, tempo de permanência e o resfriamento. Este trabalho teve como objetivo o estudo do tempo de permanência a temperatura para realização do tratamento térmico de têmpera do aço SAE 1045. Para esse fim, foram utilizados 25 corpos de provas de massas iguais, divididos em 5 grupos, e cada grupo de peças foi submetido a diferentes tempos de permanência, variando 1 hora para cada exposição. Analisando o resultado dos testes de dureza e das análises micrográficas, constatou-se que quanto maior o tempo de permanência, maior será a alteração da estrutura cristalina e também a sua dureza (resistência a penetração). Obteve-se aumento de dureza de até 346% comparando os resultados antes da realização da têmpera.
Palavras-chave: dureza; resistência mecânica; propriedades mecânicasIn order to diversify the use of common steels in the industries, it is necessary that its crystalline structure be modified, for which thermal and thermochemical treatments are carried out. To perform these treatments considered are the following factors: heating, dwell time and cooling. The objective of this study was to study the annealing temperature of SAE 1045 steel. For this purpose, 25 equal mass tests were used, divided into 5 groups and each group of pieces submitted to different residence times, varying 1 hour for each exhibition. Analyzing the results of the tests of hardness and micrographic analyzes, it was verified that the longer the permanence, the greater the change in the crystalline structure and also the hardness (resistance to penetration). A hardness increase of up to 346% was obtained by comparing the results before tempering.
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