Article
Chemistry, Physical
Emily M. Kempfer-Robertson, Andrew D. Mahler, Meagan N. Haase, Piper Roe, Lee M. Thompson
Summary: The nonorthogonal active space decomposition (NO-ASD) methodology is proposed for systems with multiple correlation mechanisms. It reduces the factorial scaling associated with the size of the correlated orbital space by partitioning the wave function and treating different correlation mechanisms with an effective Hamiltonian approach. Despite its nonorthogonal framework, NO-ASD can take advantage of efficient matrix element evaluation. Comparisons with complete active space methods show that NO-ASD has advantages in reducing problem dimensionality and recovering correlation energy.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2022)
Article
Chemistry, Physical
Tim Gould, Leeor Kronik
Summary: This study reviews two important extensions of Kohn-Sham (KS) theory: generalized KS theory and ensemble KS theory. The former allows for non-multiplicative potential operators while the latter enables the treatment of quantum ensembles, offering improvements in efficiency for practical calculations. The research combines these two extensions and explores a computationally tractable variant for handling complex scenarios.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Article
Chemistry, Physical
Tong-Hyok Cha
Summary: By introducing Structure Unit Groups (SUG) and scaling Gaussian Type Orbitals (GTOs) for core and hydrogen atoms in each SUG, this method can be applied in Hartree-Fock calculations for small molecules, reducing molecular energy and altering functional properties.
CHEMICAL PHYSICS LETTERS
(2021)
Article
Mathematics
Mohsan Raza, Sarfraz Nawaz Malik, Qin Xin, Muhey U. Din, Luminita-Ioana Cotirla
Summary: In this article, the necessary conditions for the univalence of integral operators involving two functions are studied. The conditions for the univalence of Bessel, modified Bessel, and spherical Bessel functions are included as special cases. Moreover, sufficient conditions for integral operators involving trigonometric and hyperbolic functions are provided as an application of the results.
Article
Chemistry, Physical
Tong-Hyok Cha
Summary: The paper introduces the concept of Structure Unit Group (SUG), and explains how sampled SUG-floating shifts can be used in Hartree-Fock calculations of organic molecules to lower molecular energy and cause changes in functional properties.
CHEMICAL PHYSICS LETTERS
(2021)
Article
Mathematics
Tibor K. Pogany
Summary: In this article, we establish new functional bounds and uniform bounds for the lower incomplete generalized Fox-Wright functions by using the representation formulae for the McKay I-v Bessel probability distribution's cumulative distribution function. New cumulative distribution functions are generated and expressed in terms of lower incomplete Fox-Wright functions and/or generalized hypergeometric functions. In addition, bounding inequalities are obtained for these functions.
Article
Chemistry, Physical
Hong-Zhou Ye, Timothy C. Berkelbach
Summary: In this study, distance-dependent estimators for two-center and three-center electron repulsion integrals over a short-range Coulomb potential were derived and demonstrated to be robust on periodic systems. These estimators provide tightness and are used with integral screening for calculating periodic three-center short-range Coulomb integrals with linear scaling.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Article
Chemistry, Physical
Suhwan Song, Stefan Vuckovic, Eunji Sim, Kieron Burke
Summary: Fitting parameters in approximate density functionals often leads to errors from self-consistent densities and energy functionals being conflated. However, using density-corrected DFT can separate these errors. In some cases, using Hartree-Fock densities instead of self-consistent densities can provide more accurate results at no additional cost.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2021)
Article
Chemistry, Inorganic & Nuclear
Roger E. Cramer, Jessica M. Rimsza, Timothy J. Boyle
Summary: The bond distances of [Ln(SST)3(THF)2] compounds were examined, and it was found that the Ln-O(THF) bond changed more significantly than the Ln-O(SST) bond. Further evaluations showed that this enhanced Ln-contraction also occurs in other ligands such as pyridine and halides.
INORGANIC CHEMISTRY
(2022)
Article
Engineering, Mechanical
Wenyan Guo, Yongfeng Zhi, Kai Feng
Summary: This paper introduces a new spline prioritization optimization adaptive filter algorithm to address high steady-state error in colored and/or impulsive noise environments. The algorithm uses different cost functions for linear and nonlinear parts, resulting in improved robustness. Simulation results show significant reduction in steady-state error compared to existing algorithms.
NONLINEAR DYNAMICS
(2022)
Article
Chemistry, Inorganic & Nuclear
Jialing Lan, Tonghuan Zhang, Yuhong Yang, Xin Li, Lung Wa Chung
Summary: Transition-metal-catalyzed amination of aryl halides is a useful method for synthesizing medicinal compounds, organic functional materials, and agrochemical compounds. A systematic DFT study has revealed the mechanism of Co(I)-catalyzed amination of aryl halides, with dissociative C-I activation pathway being the most favorable.
INORGANIC CHEMISTRY
(2022)
Article
Chemistry, Physical
Karan Ahmadzadeh, Mikael Scott, Manuel Brand, Olav Vahtras, Xin Li, Zilvinas Rinkevicius, Patrick Norman
Summary: In this work, computationally tractable expressions for the isotropic second-order hyperpolarizability were derived within the self-consistent field approximation. A novel tensor average formulation was used to evaluate isotropic damped cubic response functions, demonstrating a relative error of less than about 5% compared to the full form. Numerical examples for two-photon absorption cross sections in different photon resonance regions were provided, showing the effectiveness of the simplified expressions.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Article
Mathematics
Najla M. Alarifi, Saiful R. Mondal
Summary: The Bessel-Struve kernel function defined in the unit disc is studied in this article, and its generalization and related differential equations are derived. The Lemniscate convexity of the generalized Bessel-Struve function under certain conditions is identified using a subordination technique. The relationship between the Janowski class and exponential class is also established.
Article
Chemistry, Multidisciplinary
Sason Shaik, David Danovich, Richard N. Zare
Summary: This paper describes the nature of hydrogen bond using valence bond theory. The analysis shows that polarization and charge transfer are the most important interactions in hydrogen bonds, and their sum is identical for different energy decomposition analysis methods. The total covalent-ionic resonance energy of the hydrogen bond is linearly correlated with the dissociation energy of the bond. The contributions of ionic structures to the hydrogen bond increase the positive charge on the hydrogen and contribute to catalytic reactions.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Engineering, Electrical & Electronic
Alireza Naeimi Sadigh, Hadi Zayyani
Summary: In this paper, an improved version of the proportionate robust diffusion recursive least exponential hyperbolic cosine algorithm is proposed. The step-size parameter of this algorithm is optimally selected by minimizing the squared norm of the error vector. Theoretical analysis is performed to study the mean-square convergence, mean-square steady-state, and forgetting factor parameter selection, and simulation experiments demonstrate that the improved algorithm outperforms the original algorithm and other state-of-the-art algorithms in terms of convergence speed.
IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS II-EXPRESS BRIEFS
(2023)