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density functional theory

M Mougeot, D Atanasov, K Blaum, K Chrysalidis, T Day Goodacre, D Fedorov, V Fedosseev, S George, F Herfurth, J D Holt, D Lunney, V Manea, B Marsh, D Neidherr, M Rosenbusch, S Rothe, L Schweikhard, A Schwenk, C Seiffert, J Simonis, S R Stroberg, A Welker, F Wienholtz, R N Wolf, K Zuber
The neutron-rich isotopes ^{58-63}Cr were produced for the first time at the ISOLDE facility and their masses were measured with the ISOLTRAP spectrometer. The new values are up to 300 times more precise than those in the literature and indicate significantly different nuclear structure from the new mass-surface trend. A gradual onset of deformation is found in this proton and neutron midshell region, which is a gateway to the second island of inversion around N=40. In addition to comparisons with density-functional theory and large-scale shell-model calculations, we present predictions from the valence-space formulation of the ab initio in-medium similarity renormalization group, the first such results for open-shell chromium isotopes...
June 8, 2018: Physical Review Letters
Kohsuke Mori, Taiki Sano, Hisayoshi Kobayashi, Hiromi Yamashita
The hydrogenation of carbon dioxide (CO2 ) to formic acid (FA; HCOOH), a renewable hydrogen storage material, is a promising means of realizing an economical CO2 -mediated hydrogen energy cycle. The development of reliable heter-ogeneous catalysts is an urgent yet challenging task associated with such systems, although precise catalytic site design protocols are still lacking. In the present study, we demonstrate that PdAg alloy nanoparticles (NPs) supported on TiO2 promote the efficient selective hydrogenation of CO2 to give FA even under mild reaction conditions (2...
June 22, 2018: Journal of the American Chemical Society
Ying-Tao Liu, Xue Yin, Xiao-Yong Lai, Xin Wang
Two-photon photodynamic therapy (TP-PDT) is a very promising treatment that has drawn much attention in recent years due to its ability to penetrate deeper into tissues and minimize the damage to normal cells. Here, the properties of three highly water soluble Ru(ii) and Zn(ii) polypyridyl complexes as photosensitizers (PSs) were examined, including the one-photon and two-photon absorption (OPA and TPA) spectra, singlet-triplet energy gap (ΔH-L), TPA cross-section and spin-orbit coupling constant via Density Function Theory (DFT) and Time-Dependent Density Functional Theory (TD-DFT)...
June 22, 2018: Physical Chemistry Chemical Physics: PCCP
Beata Jedrzejewska, Agnieszka Skotnicka, Adèle D Laurent, Marek Pietrzak, Denis Jacquemin, Borys Osmialowski
A series of difluoroborates were synthesized from CH-acids. All compounds were substituted by dialkylamino groups (NR2). The lone electron pair of the nitrogen atom of this donor moiety is variably delocalized towards the difluoroborate core that acts as the electron acceptor. This was rationalized in the light of the various geometries of the amino group. The degree of charge-transfer was quantified based on the results of Time-Dependent Density Functional Theory (TD-DFT) calculations.
June 22, 2018: Journal of Organic Chemistry
Han Chu, Wenzhong Wu, Youxiang Shao, Yizhen Tang, Yunju Zhang, Yinfang Cheng, Fang Chen, Jiangyan Liu, Jingyu Sun
The hydroxyl radical, as the most important oxidant, controls the removal of some volatile organic compounds (VOCs) in the atmosphere. In this work, the atmospheric oxidation processes of acrylic acid by OH radical have been investigated by density functional theory (DFT). The energetic routes of the reaction of CH2 CHCOOH with OH radical have been calculated accurately at the CCSD(T)/cc-pVTZ//M06-2X/6-311++G(d,p) level. It is implicated that the oxidation has five elementary reaction pathways mostly hinging on how hydroxyl radical approaches to the carbon skeleton of acrylic acid...
June 21, 2018: Environmental Science and Pollution Research International
Ryan Smith, Anna Sanova, Anna Alkozei, Richard D Lane, William D S Killgore
Previous studies have suggested that trait differences in emotional awareness (tEA) are clinically relevant, and associated with differences in neural structure/function. While multiple leading theories suggest that conscious awareness requires widespread information integration across the brain, no study has yet tested the hypothesis that higher tEA corresponds to more efficient brain-wide information exchange. Twenty-six healthy volunteers (13 female) underwent a resting state functional magnetic resonance imaging scan, and completed the Levels of Emotional Awareness Scale (LEAS; a measure of tEA) and the Wechsler Abbreviated Scale of Intelligence (WASI-II; a measure of general intelligence [IQ])...
June 21, 2018: Social Cognitive and Affective Neuroscience
Bo Wen, Qunqing Hao, Wen-Jin Yin, Le Zhang, Zhiqiang Wang, Tianjun Wang, Chuanyao Zhou, Annabella Selloni, Xueming Yang, Li-Min Liu
We have used two-photon photoemission (2PPE) spectroscopy and first-principles density functional theory calculations to investigate the electronic structure and photoabsorption of the reduced anatase TiO2(101) and rutile TiO2(110) surfaces. 2PPE measurements on anatase (101) show an excited resonance induced by reduced Ti3+ species centered around 2.5 eV above the Fermi level (EF). While this state is similar to that observed on the rutile (110) surface, the intensity of the 2PPE peak is much weaker. The computed oscillator strengths of the transitions from the occupied gap states to the empty states in the conduction band show peaks between 2...
June 22, 2018: Physical Chemistry Chemical Physics: PCCP
Yu Zhu, Depeng Zhang, Zhanwen Zhang, Zhigang Wang
The widespread application of hydrocarbon polymer materials has spurred an increasing interest in the study of their dissociation mechanism, which is related to key issues such as environmental protection. In this work, the last-step dissociation characteristics of carbon chain polymers were investigated. By using density functional theory, we considered all possible structures, including three typical normal linkage polymers and four typical abnormal linkage ones. In these structures, it can be found that the energy barrier required for the complete degradation of chain-end saturated and unsaturated polymers are in the range of 3...
June 2018: ChemistryOpen
D Wu, B L Qiu, C Q Zhu, S Guo, Y Y Gaoyang, Q H Liang, Y Gao, Y Song, N Y Han
OBJECTIVE: To analyze and characterize the separation effectiveness of self-constructed asymmetrical flow field-flow fractionation system on proteins and lipoproteins, to achieve the optimization of the experimental conditions when separating lipoproteins by orthogonal design test and to investigate the carrier viscosity's influence on separation effectiveness. METHODS: The evaluation of asymmetrical flow field-flow fractionation separation capacity was conducted by using two standard proteins (carbonic anhydrase and thyroglobulin)...
June 18, 2018: Beijing da Xue Xue Bao. Yi Xue Ban, Journal of Peking University. Health Sciences
Huan Tang, Ying Zhao, Sujie Shan, Xiaonan Yang, Dongmei Liu, Fuyi Cui, Baoshan Xing
In this work, the favorable adsorption sites of aromatic compounds (ACs) on graphene oxide (GO) are characterized with both experimental and theoretical approaches. The results show that ACs exhibit a strong preference in adsorbing near the wrinkles and edges. Further analyses reveal that the edge-adsorption is mainly guided by the stronger π-π interaction near edges, accompanied by a stronger hydrogen bond interaction between carboxyl groups and ACs. Additionally, the water-mediated steric hindrance and flexibility of carboxyl groups also contribute to the edge-adsorption...
June 21, 2018: Environmental Science & Technology
Isiaka A Lawal, Monsurat M Lawal, Samson O Akpotu, Mayowa A Azeez, Patrick Ndungu, Brenda Moodley
The adsorption of sulfamethoxazole (SMZ) and ketoprofen (KET) using carbon nanotubes (CNTs) and CNTs modified with ionic liquids (ILs) was investigated. Two ionic liquids (1-benzyl, 3-hexyl imidazolium, IL1 and 1-benzyl, 3-decahexyl imidazolium, IL2) were synthesized, and characterized by nuclear magnetic resonance (1 H and 13 C NMR) and high resolution-mass spectrometry (HR-MS). CNTs and modified CNTs were characterized using FT-IR, X-ray diffraction (XRD), surface area and porosity analysis, thermal gravimetric analysis (TGA), Zeta potential, Raman and scanning electron microscopy (SEM)...
June 18, 2018: Ecotoxicology and Environmental Safety
Stefania Vergura, Ernesto Santoro, Marco Masi, Antonio Evidente, Patrizia Scafato, Stefano Superchi, Giuseppe Mazzeo, Giovanna Longhi, Sergio Abbate
Jonquailine, a new alkaloid recently isolated from Narcissus jonquilla quail, an Amaryllidacea species cultivated for its fragrance flowers in Europe and USA, shows very significant anti-proliferative activity against several malignant cancer cell types. Although it was reported that this activity is related to the functionalities and to its stereochemistry at C-8 of B ring, the absolute configuration at this stereocenter was not known. Density functional theory (DFT) calculations of chiroptical properties, namely electronic circular dichroism (ECD), vibrational circular dichroism (VCD), and optical rotatory dispersion (ORD) are employed here to complete assignment of absolute configuration of jonquailine, and then, by extension, to its analogues pretazettine and 8-O-methylpretazettine...
June 18, 2018: Fitoterapia
Omar Allam, Colin Homles, Zev Greenberg, Ki Chul Kim, Seung Soon Jang
In this study, we have developed a protocol for exploring the vast chemical space of possible perovskites and screening the promising candidates. Furthermore, we examined factors that af-fect the band gap energies of perovskites. Goldschmidt tolerance factor and octahedral factor ranges of 0.98 to 1 and 0.45 to 0.7, respectively, are used to filter only highly cubic perovskites that are stable at room temperature. After removing rare or radioactively unstable elements, quan-tum mechanical density functional theory calculations are performed on remaining perovskites to assess whether their electronic properties such as band structure are suitable for solar cell applica-tions...
June 21, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Xue Li, Yanyan Wang, Yang Wang, Mingsheng Tang, Ling-Bo Qu, Zhongjun Li, Donghui Wei
The N-heterocyclic carbene (NHC)-catalyzed oxidative C-H deprotonations have attracted increasing attention; however, the general mechanism regarding this kind of oxidative organocatalysis remains unclear. In this paper, the competing mechanisms and origin of the stereoselectivity of the NHC-catalyzed oxidative γ-C(sp3)-H deprotonation of alkylenals and cascade [4 + 2] cycloaddition with alkenylisoxazoles were systematically investigated for the first time using density functional theory (DFT). The computed results indicate that the oxidation of the Breslow intermediate by 3,3',5,5'-tetra-tert-butyl diphenoquinone (DQ) via a hydride transfer to oxygen (HTO) pathway is the most favorable among the four competing pathways...
June 21, 2018: Journal of Organic Chemistry
Chunying Rong, Dongbo Zhao, Donghai Yu, Shubin Liu
Cooperativity is a widely used chemical concept whose existence is ubiquitous in chemical and biological systems but whose quantification is still controversial and origin much less appreciated. In this work, using the interaction energy of a molecular system, which is composed of multiple copies of a building block, we propose a quantitative measurement to evaluate the cooperativity effect. This quantification approach is then applied to six molecular systems, i.e., water cluster, argon cluster, protonated water cluster, zinc atom cluster, water cluster on top of a graphene sheet, and alpha helix of glycine amino acids, each with up to 20 copies of the building block...
June 21, 2018: Physical Chemistry Chemical Physics: PCCP
Tohru Taniguchi, Kie Nakano, Kenji Monde
The chemistry of artificial nucleosides is associated with the difficulties in the characterization of the stereochemistry and conformation of their furanose ring moiety. This unit describes how to use vibrational circular dichroism (VCD) spectroscopy to identify the three-dimensional structure of nucleosides. The experimental part of this protocol is dedicated to obtain a VCD spectrum of a sample with high S/N ratio. The computational part generally starts with a conformational search using molecular mechanics and the following structural optimization by density functional theory calculation...
March 2018: Current Protocols in Nucleic Acid Chemistry
Qing Guo, Gaoxue Wang, Ravindra Pandey, Shashi P Karna
The applicability of graphene in nanoscale devices is somewhat limited because of the absence of a finite band gap. To overcome this limitation of zero band gap, we consider vertically-stacked heterostructures consisting of graphene and SnO knowing that two-dimensional SnO films were synthesized recently. Calculations based on density functional theory find that the oxide monolayer can induce a notable band gap in graphene; 115 meV in SnO/graphene/SnO heterostructures. Additionally, the band gap of graphene can be maintained under a relatively high electric field (≈109 V m-1) applied to the heterostructures because of the electrostatic screening effect of the oxide layer...
June 21, 2018: Physical Chemistry Chemical Physics: PCCP
Olga A Stasyuk, Robert Sedlak, Célia Fonseca Guerra, Pavel Hobza
Interaction energies computed with density functional theory can be divided into physically meaningful components by symmetry-adapted perturbation theory (DFT-SAPT) or the canonical energy decomposition analysis (EDA). In this work, the decomposition results obtained by these schemes were compared for more than 200 hydrogen-, halogen-, and pnicogen-bonded, dispersion-bound, and mixed complexes to investigate their similarity in the evaluation of the nature of noncovalent interactions. BLYP functional with D3(BJ) correction was used for the EDA scheme, whereas asymptotically corrected PBE0 functional for DFT-SAPT provided some of the best combinations for description of noncovalent interactions...
June 21, 2018: Journal of Chemical Theory and Computation
Zeyu Liu, Li Zhang, Xian Wang, Gang Jiang, Mingli Yang
Introduction of silicon into hydroxyapatite (HA) is one of the effective ways to modulate the bioactivity of HA-based biomaterials. The bulk and surface structures of silicate-substituted HA (Si-HA) were characterized by using density functional theory calculations. The energetically favorable structures were identified from a number of candidate structures. Particular attention was paid to the surface structures of Si-HA, whose bioactivity is closely relevant to their surface atoms. Compared to the surface of pure HA, the Si-HA surface has similar surface energy but different charge distribution...
June 20, 2018: Journal of Molecular Modeling
Tiantian Xue, Chao Wu, Xiangdong Ding, Jun Sun
The adsorption and dissociation of O2 and the adsorption of O* adatoms over strained Pt(111) surfaces have been systematically studied using density functional theory calculations. When the applied bilateral strain ranges from compressive (-5%) to tensile (5%), the adsorption strengths of O and O2 at various sites can be varied substantially by 0.3 to 0.9 eV. Moreover, the preferred adsorption site of O2 also changes from tbt to tfb when tensile strain is larger than 3%. The activation barrier of O2 dissociation can be significantly varied by nearly 0...
June 21, 2018: Physical Chemistry Chemical Physics: PCCP
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