keyword
https://read.qxmd.com/read/38534023/modeling-of-high-harmonic-generation-in-the-c-60-fullerene-using-ab-initio-dft-based-and-semiempirical-methods
#1
JOURNAL ARTICLE
Aleksander P Woźniak, Robert Moszyński
We report calculations of the high-harmonic generation spectra of the C60 fullerene molecule carried out by employing a diverse set of real-time time-dependent quantum chemical methods. All methodologies involve expanding the propagated electronic wave function in bases consisting of the ground and singly excited time-independent eigenstates obtained through the solution of the corresponding linear-response equations. We identify the correlation and exchange effect in the spectra by comparing the results from methods relying on the Hartree-Fock reference determinant with those obtained using approaches based on the density functional theory with different exchange-correlation functionals...
March 27, 2024: Journal of Physical Chemistry. A
https://read.qxmd.com/read/38533827/doubly-charged-dimers-and-trimers-of-heavy-noble-gases
#2
JOURNAL ARTICLE
Gabriel Schöpfer, Stefan Bergmeister, Milan Ončák, Ianessa Stromberg, Masoomeh Mahmoodi-Darian, Paul Scheier, Olof Echt, Elisabeth Gruber
Many doubly charged heteronuclear dimers are metastable or even thermodynamically stable with respect to charge separation. Homonuclear dicationic dimers, however, are more difficult to form. He2 2+ was the first noble gas dimer predicted to be metastable and, decades later, observed. Ne2 2+ is the only other dicationic noble gas dimer that has been detected so far. Here, we present a novel approach to form fragile dicationic species, by post-ionization of singly charged ions that are embedded in helium nanodroplets (HNDs)...
March 27, 2024: Physical Chemistry Chemical Physics: PCCP
https://read.qxmd.com/read/38532730/the-thermal-decomposition-mechanism-of-rdx-ap-composites-ab-initio-neural-network-md-simulations
#3
JOURNAL ARTICLE
Kehui Pang, Mingjie Wen, Xiaoya Chang, Yabei Xu, Qingzhao Chu, Dongping Chen
A neural network potential (NNP) is developed to investigate the decomposition mechanism of RDX, AP, and their composites. Utilizing an ab initio dataset, the NNP is evaluated in terms of atomic energy and forces, demonstrating strong agreement with ab initio calculations. Numerical stability tests across a range of timesteps reveal excellent stability compared to the state-of-the-art ReaxFF models. Then the thermal decomposition of pure RDX, AP, and RDX/AP composites is performed using NNP to explore the coupling effect between RDX and AP...
March 27, 2024: Physical Chemistry Chemical Physics: PCCP
https://read.qxmd.com/read/38531828/first-principles-models-of-polymorphism-of-pharmaceuticals-maximizing-the-accuracy-to-cost-ratio
#4
JOURNAL ARTICLE
Jan Ludík, Veronika Kostková, Štefan Kocian, Petr Touš, Vojtěch Štejfa, Ctirad Červinka
Accuracy and sophistication of in silico models of structure, internal dynamics, and cohesion of molecular materials at finite temperatures increase over time. Applicability limits of ab initio polymorph ranking that would be feasible at reasonable costs currently represent crystals of moderately sized molecules (less than 20 nonhydrogen atoms) and simple unit cells (containing rather only one symmetry-irreducible molecule). Extending the applicability range of the underlying first-principles methods to larger systems with a real-life significance, and enabling to perform such computations in a high-throughput regime represent additional challenges to be tackled in computational chemistry...
March 26, 2024: Journal of Chemical Theory and Computation
https://read.qxmd.com/read/38530754/lithium-grafted-si-doped-%C3%AE-graphyne-as-a-reversible-hydrogen-storage-host-material
#5
JOURNAL ARTICLE
Nidhi Duhan, T J Dhilip Kumar
In recent years, hydrogen (H2 ) has become the most sought-after sustainable energy carrier by virtue of its high energy content and carbon-free emission. The practical implementation of hydrogen as an alternative fuel calls for an efficient and secure storage medium. Within this framework, we have investigated Li-grafted Si-doped γ-graphyne for H2 storage applications by implementing the cutting-edge density functional theory (DFT). A dynamically and thermally stable Si-doped γ-graphyne (SiG) monolayer is functionalized with Li metal atoms that augmented the hydrogen binding strength of the nanolayer by almost three times, owing to the polarization effect of the Li atoms...
March 26, 2024: Physical Chemistry Chemical Physics: PCCP
https://read.qxmd.com/read/38530340/ozonolysis-of-2-methyl-2-pentenal-new-insights-from-master-equation-modeling
#6
JOURNAL ARTICLE
Najoua Derbel, Carmen Kalalian, Alexander Alijah, Struan H Robertson, Abdelkhaleq Chakir, Estelle Roth
Experimental and theoretical studies were carried out to investigate the ozonolysis of trans -2-methyl-2-pentenal. The experiments were conducted in atmospheric simulation chambers coupled to a Fourier transform infrared (FTIR) spectrometer and a gas chromatograph-mass spectrometer at room temperature and atmospheric pressure in the presence of an excess of cyclohexane in dry conditions (RH < 1%). The ozonolysis reaction was investigated theoretically from the results of accurate density functional (M06-2X) and ab initio [CCSD(T)] computations, employing the AVTZ basis set...
March 26, 2024: Journal of Physical Chemistry. A
https://read.qxmd.com/read/38530253/vibrational-dynamics-and-spectroscopy-of-water-at-porous-g-c-3-n-4-and-c-2-n-surfaces
#7
JOURNAL ARTICLE
Deepak Ojha, Christopher Penschke, Peter Saalfrank
Porous graphitic materials containing nitrogen are promising catalysts for photo(electro)chemical reactions, notably water splitting, but can also serve as "molecular sieves". Nitrogen increases the hydrophilicity of the graphite parent material, among other effects. A deeper understanding of how water interacts with C- and N-containing layered materials, if and which differences exist between materials with different N content and pore size, and what the role of water dynamics is - a prerequsite for catalysis and sieving - is largely absent, however...
March 26, 2024: Physical Chemistry Chemical Physics: PCCP
https://read.qxmd.com/read/38530009/phonon-mediated-ultrafast-energy-and-momentum-resolved-hole-dynamics-in-monolayer-black-phosphorus
#8
JOURNAL ARTICLE
Siyuan Gao, Yu-Chen Wang, Yi Zhao
The electron-phonon scattering plays a crucial role in determining the electronic, transport, optical, and thermal properties of materials. Here, we employ a non-Markovian stochastic Schrödinger equation (NMSSE) in momentum space, together with ab initio calculations for energy bands and electron-phonon interactions, to reveal the phonon-mediated ultrafast hole relaxation dynamics in the valence bands of monolayer black phosphorus. Our numerical simulations show that the hole can initially remain in the high-energy valence bands for more than 100 fs due to the weak interband scatterings, and its energy relaxation follows single-exponential decay toward the valence band maximum after scattering into low-energy valence bands...
March 28, 2024: Journal of Chemical Physics
https://read.qxmd.com/read/38529563/spontaneous-wetting-induced-by-contact-electrification-at-liquid-solid-interface
#9
JOURNAL ARTICLE
Zhen Tang, Dan Yang, Hengyu Guo, Shiquan Lin, Zhong Lin Wang
Wettability significantly influences various surface interactions and applications at the liquid-solid interface. However, our understanding is complicated by the intricate charge exchange occurring through contact electrification (CE) during this process. The understanding of the influence of triboelectric charge on wettability remains challenging, especially due to the complexities involved in concurrently measuring contact angles and interfacial electrical signals. Here, we investigate the relationship between surface charge density and change of contact angle of dielectric films after contact with water droplets...
March 26, 2024: Advanced Materials
https://read.qxmd.com/read/38528393/visualizing-noncovalent-interactions-and-property-prediction-of-submicron-sized-charge-transfer-crystals-from-ab-initio-determined-structures
#10
JOURNAL ARTICLE
Zhong-Peng Lv, Divya Srivastava, Kevin Conley, Tero-Petri Ruoko, Hongyi Xu, Molly Lightowler, Xiaodan Hong, Xiaoqi Cui, Zhehao Huang, Taimin Yang, Hai-Ying Wang, Antti J Karttunen, Lennart Bergström
The charge-transfer (CT) interactions between organic compounds are reflected in the (opto)electronic properties. Determining and visualizing crystal structures of CT complexes are essential for the design of functional materials with desirable properties. Complexes of pyranine (PYR), methyl viologen (MV), and their derivatives are the most studied water-based CT complexes. Nevertheless, very few crystal structures of CT complexes have been reported so far. In this study, the structures of two PYRs-MVs CT crystals and a map of the noncovalent interactions using 3D electron diffraction (3DED) are reported...
March 25, 2024: Small Methods
https://read.qxmd.com/read/38526528/global-potential-energy-surfaces-by-compressed-state-multistate-pair-density-functional-theory-for-hyperthermal-collisions-in-the-o2-o2-system
#11
JOURNAL ARTICLE
Jie Jiang, Jiawei Yang, Qizhen Hong, Quanhua Sun, Jun Li
Interactions between oxygen molecules play an important role in atmospheric chemistry and hypersonic flow chemistry in atmospheric entries. Recently, high-quality ab initio potential energy surface (PES) of the quintet O4 was reported by Paukku et al. [J. Chem. Phys. 147, 034301 (2017)]. 10543 configurations were sampled and calculated at the level of MS-CASPT2/maug-cc-pVTZ with scaled external correlation. The PES was fitted to a many-body (MB) form with the many-body part described by the permutationally invariant polynomial approach (MB-PIP)...
March 25, 2024: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
https://read.qxmd.com/read/38526510/-ab-initio-calculations-of-the-spectra-and-lifetimes-of-the-lead-dimer
#12
JOURNAL ARTICLE
Lidan Xiao, Boris F Minaev, Hans Ågren, Bing Yan
Owing to the key role of the lead dimer (Pb2 ) as a heavy element benchmark for the Group IV-A dimers the assignment of its spectroscopic properties and chemical bonding is an important undertaking. To meet this demand, the present work provides comprehensive and detailed information on electronic structure and properties comprising a wide set of Pb2 states. Calculations are performed by a high-level ab initio approach. Firstly, the potential energy curves (PECs) of 19 Λ-S states as well as those of 24 ungerade Ω states are calculated by utilizing the multi-reference configuration interaction plus Davidson correction (MRCI + Q) method taking into account core-valence correlation (CV) and spin-orbit coupling (SOC) effect, where Ω is a quantum number of the total (Λ + S) angular momentum projection...
March 25, 2024: Physical Chemistry Chemical Physics: PCCP
https://read.qxmd.com/read/38526437/the-mechanism-and-kinetics-of-the-atmospheric-oxidation-of-cf-3-cf-2-2-ch%C3%AE-ch-2-hfc-1447fz-by-hydroxyl-radicals-ab-initio-investigation
#13
JOURNAL ARTICLE
Youqing Yu, Li Pan, Qiyao Sun, Jie Wang
The oxidation of 3,3,4,4,5,5,5-heptafluoro-1-pentene (HFC-1447fz) by hydroxyl radicals plays a crucial role in atmospheric conditions. By employing the CCSD(T)/cc-pVTZ//M06-2X/6-311++G(d,p) level of theory, the detailed reaction mechanism, kinetics and atmospheric implications of the degradation of HFC-1447fz by hydroxyl radicals were investigated. Compared to H-abstraction channels, the OH addition reaction is determined to be more favorable initial pathways in the degradation processes of HFC-1447fz. The overall rate coefficient of the degradation of HFC-1447fz by OH radicals is estimated to be 1...
March 25, 2024: Physical Chemistry Chemical Physics: PCCP
https://read.qxmd.com/read/38526114/practical-phase-space-electronic-hamiltonians-for-ab%C3%A2-initio-dynamics
#14
JOURNAL ARTICLE
Zhen Tao, Tian Qiu, Mansi Bhati, Xuezhi Bian, Titouan Duston, Jonathan Rawlinson, Robert G Littlejohn, Joseph E Subotnik
Modern electronic structure theory is built around the Born-Oppenheimer approximation and the construction of an electronic Hamiltonian Ĥel(X) that depends on the nuclear position X (and not the nuclear momentum P). In this article, using the well-known theory of electron translation (Γ') and rotational (Γ″) factors to couple electronic transitions to nuclear motion, we construct a practical phase-space electronic Hamiltonian that depends on both nuclear position and momentum, ĤPS(X,P)...
March 28, 2024: Journal of Chemical Physics
https://read.qxmd.com/read/38526104/noise-independent-route-toward-the-genesis-of-a-compact-ansatz-for-molecular-energetics-a-dynamic-approach
#15
JOURNAL ARTICLE
Dipanjali Halder, Dibyendu Mondal, Rahul Maitra
Recent advances in quantum information and quantum science have inspired the development of various compact, dynamically structured ansätze that are expected to be realizable in Noisy Intermediate-Scale Quantum (NISQ) devices. However, such ansätze construction strategies hitherto developed involve considerable measurements, and thus, they deviate significantly in the NISQ platform from their ideal structures. Therefore, it is imperative that the usage of quantum resources be minimized while retaining the expressivity and dynamical structure of the ansatz that can adapt itself depending on the degree of correlation...
March 28, 2024: Journal of Chemical Physics
https://read.qxmd.com/read/38525554/on-local-structure-equilibration-of-ca-2-in-solution-by-ab-initio-molecular-dynamics
#16
JOURNAL ARTICLE
Hugo Moison, Julie Aufort, Magali Benoit, Merlin Méheut
Analyzing the stable isotopic ratio of Ca offers valuable insights into a wide range of applications from climate reconstruction to bone cancer diagnosis and agricultural nutrient improvement. While the first hydration shell of Ca in solution is expected to play a major role in its fractionation properties, the coordination of Ca in water remains a subject of debate. In this work, Ca2+ in water has been modeled by means of ab initio molecular dynamics simulations using various exchange and correlation functionals and at different temperatures...
March 25, 2024: Journal of Physical Chemistry. B
https://read.qxmd.com/read/38525498/photoswitching-of-arylazopyrazoles-upon-s-1-n%C3%AF-excitation-studied-by-transient-absorption-spectroscopy-and-ab-initio-molecular-dynamics
#17
JOURNAL ARTICLE
Till Reichenauer, Marcus Böckmann, Katharina Ziegler, Vikas Kumar, Bart Jan Ravoo, Nikos L Doltsinis, Sebastian Schlücker
Arylazopyrazoles (AAPs) are an important class of molecular photoswitches with high photostationary states (PSS) and long thermal lifetimes. The ultrafast photoisomerization of four water-soluble arylazopyrazoles, all of them featuring an ortho -dimethylated pyrazole ring, is studied by narrowband femtosecond transient absorption spectroscopy and ab initio molecular dynamics simulations. Upon S1 (nπ*) photoexcitation of the planar E -isomers ( E -AAPs), excited-state bi-exponential decays with time constants τ 1 in the 220-440 fs range and τ 2 in the 1...
March 25, 2024: Physical Chemistry Chemical Physics: PCCP
https://read.qxmd.com/read/38522710/small-angle-x-ray-scattering-analysis-of-thermophilic-cytochrome-p450-cyp119-and-the-effects-of-the-n-terminal-histidine-tag
#18
JOURNAL ARTICLE
Ekin Kestevur Doğru, Tuğçe Sakallı, Goksin Liu, Zehra Sayers, Nur Basak Surmeli
Combining size exclusion chromatography-small angle X-ray scattering (SEC-SAXS) and molecular dynamics (MD) analysis is a promising approach to investigate protein behavior in solution, particularly for understanding conformational changes due to substrate binding in cytochrome P450s (CYPs). This study investigates conformational changes in CYP119, a thermophilic CYP from Sulfolobus acidocaldarius that exhibits structural flexibility similar to mammalian CYPs. Although the crystal structure of ligand-free (open state) and ligand-bound (closed state) forms of CYP119 is known, the overall structure of the enzyme in solution has not been explored until now...
March 22, 2024: International Journal of Biological Macromolecules
https://read.qxmd.com/read/38521041/iron-nuclearity-in-mineral-fibres-unravelling-the-catalytic-activity-for-predictive-modelling-of-toxicity
#19
JOURNAL ARTICLE
Alessandro F Gualtieri, Marina Cocchi, Francesco Muniz-Miranda, Alfonso Pedone, Elena Castellini, Lorenzo Strani
Chronic inflammation induced in vivo by mineral fibres, such as asbestos, is sustained by the cyclic formation of cytotoxic/genotoxic oxidant species that are catalysed by iron. High catalytic activity is observed when iron atoms are isolated in the crystal lattice (nuclearity=1), whereas the catalytic activity is expected to be reduced or null when iron forms clusters of higher nuclearity. This study presents a novel approach for systematically measuring iron nuclearity across a large range of iron-containing standards and mineral fibres of social and economic importance, and for quantitatively assessing the relation between nuclearity and toxicity...
March 11, 2024: Journal of Hazardous Materials
https://read.qxmd.com/read/38520354/toward-atomistic-understanding-of-iron-phosphate-glass-a-first-principles-based-density-functional-theory-modeling-and-study-of-its-physical-properties
#20
JOURNAL ARTICLE
Shakti Singh, Manan Dholakia, Sharat Chandra
Iron phosphate glasses (IPGs) have been proposed as futuristic materials for nuclear waste immobilization and anode materials for lithium batteries. Recently, many attempts have been made to propose atomistic models of IPGs to explain their properties from an atomistic viewpoint. In this paper, we seek to produce small scale models of IPG that can be handled within the scheme of density functional theory (DFT) to study its electronic structure. The starting models, generated using the Monte Carlo (MC) method, were subsequently annealed using ab initio molecular dynamics (AIMD) to minimize the coordination defects...
March 23, 2024: Journal of Physical Chemistry. B
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