Article
Chemistry, Physical
Nils Herrmann, Michael Hanrath
Summary: In this paper, a novel coupled cluster singles and doubles (CCSD) implementation for arbitrary high-spin open-shell states is reported. The chosen cluster operator is completely spin-free and employs spatial substitutions only. The implementation relies on second quantization and factorized tensor contractions. The generated operators are embedded in an equation generation engine using Wick's theorem for spin integration. The resulting method, denoted as SASC-CCSD, shows reasonable convergence and slightly improved correlation energies compared to spin orbital CCSD.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Chemistry, Physical
Ehsan Masumian, A. Daniel Boese
Summary: This study investigates the role of pi-resonance in the enhancement of intramolecular hydrogen bonds (IMHBs) by comparing pi-conjugated systems to their saturated planar counterparts. The results show that pi-resonance primarily affects the induction and electrostatics contributions to the IMHB energies. The stabilization of IMHBs is achieved by reducing the repulsion caused by the exchange term. These findings are consistent with expected trends in resonance assisted hydrogen bonds (RAHBs) and validate the fragmentation procedures used in this study.
Article
Astronomy & Astrophysics
Y. Unal, D. Severt, J. de Vries, C. Hanhart, Ulf-G Meissner
Summary: Triggered by experimental prospects, this study calculates the CP-odd electric dipole moments (EDMs) of spin-1/2 single-bottom baryons and discusses the expected size of the EDMs for beyond-the-Standard-Model physics appearing at the TeV scale.
Article
Chemistry, Physical
M. A. Ambroise, F. Sacchetta, D. Graf, C. Ochsenfeld, A. Dreuw
Summary: A novel local approach is proposed for the quantum-chemical computation of excited states by extending the atomic-orbital formulation to the second-order algebraic diagrammatic construction scheme using Laplace transform. The CDD-DF-SOS-ADC(2) method achieves substantial reduction in computational effort by exploiting the sparsity of two-electron repulsion integrals, atomic ground-state density matrix, and atomic transition density matrix. It is shown that asymptotically linear scaling can be achieved for linear carboxylic acids, and sub-cubic scaling can be achieved for electron-dense systems with sparse transition density. The memory footprint and accuracy of the method are also explored.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Astronomy & Astrophysics
Xiong-Hui Cao, Qu-Zhi Li, Zhi-Hu Guo, Han-Qing Zheng
Summary: In this study, an extended Roy equation is used to investigate ππ scatterings at unphysical large pion masses, where σ becomes a bound state in one situation and remains a broad resonance in another case. The coupled integral equations at large pion masses are solved by considering lattice driving terms and Regge amplitudes as inputs. Using the solutions of Roy equations that satisfy unitarity, analyticity, and crossing symmetry, we make predictions for the phase shifts with IJ = 00, 11, and 20 in the elastic energy region. We then analytically continue into the complex s plane to search for various poles, all of which lie within the valid domain of the Roy equation. This is the first time that lattice data at unphysical large pion masses are analyzed using the rigorous Roy equation method.
Article
Computer Science, Interdisciplinary Applications
Honghui Shang, WanZhen Liang, Yunquan Zhang, Jinlong Yang
Summary: A new method for calculating response properties related to atomic displacement and electric field perturbation, based on real-space density-functional perturbation theory (DFPT), has been developed and implemented. The computation bottleneck of the response density matrix has been identified and a more efficient algorithm has been proposed, reducing the formal scaling from O(N-3) to O(N) with good parallel scalability. Validation has shown rapid and accurate computation of polarizabilities using DFPT, with computational efficiency demonstrated on massively parallel computer systems.
COMPUTER PHYSICS COMMUNICATIONS
(2021)
Article
Chemistry, Physical
Ren A. Wiscons, Rahul Nikhar, Krzysztof Szalewicz, Adam J. Matzger
Summary: This study compares hydrates and hydrogen peroxide solvates in terms of their structure, interaction, and impact on the performance of drugs and explosives. By analyzing crystal structures and potential energy surfaces, the research provides a foundation for designing and selecting candidate molecules for hydrogen peroxide solvates.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2022)
Article
Biochemistry & Molecular Biology
Krzysztof Szalewicz, Bogumil Jeziorski
Summary: SAPT is a method for computational studies of noncovalent interactions, providing clear physical interpretations and specific dependence on intermolecular separation. It connects interaction energies with monomers' properties through the asymptotic multipole expansion.
JOURNAL OF MOLECULAR MODELING
(2022)
Article
Astronomy & Astrophysics
Hao Liu, Yuan-He Zou, Yan-Rui Liu, Shao-Zhou Jiang
Summary: The relativistic chiral Lagrangians for doubly charmed baryons of spin-1/2 and spin-3/2 are constructed up to the order O(p(4)). There are a total of 19, 74, and 452 independent terms in the two-flavor case and 25, 112, and 864 independent terms in the three-flavor case from O(p(2)) to O(p(4)). The chiral Lagrangians in the heavy diquark limit are also obtained.
Article
Chemistry, Physical
Tamar Goldzak, Xiao Wang, Hong-Zhou Ye, Timothy C. Berkelbach
Summary: In this study, the performance of spin-component-scaled second-order Møller-Plesset perturbation theory (SCS-MP2) for the prediction of lattice constant, bulk modulus, and cohesive energy of simple covalent and ionic semiconductors and insulators was investigated. The results show that SCS-MP2 and the simpler scaled opposite-spin MP2 (SOS-MP2) method yield significantly improved predictions compared to MP2, with mean absolute errors smaller than those of leading density functionals. The reparameterization of the spin scaling parameters suggests good transferability and potential applications to surface chemistry on insulators.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Astronomy & Astrophysics
Anvy Moly Tom, Rathul Nath Raveendran
Summary: This study investigates the damped superimposed oscillations in the primodial power spectrum generated by both single field and two field models. By utilizing the generalized slow roll approximation, the authors successfully reconstruct single field models based on the features commonly generated in two field models, and validate their methodology by numerical calculation.
PHYSICS OF THE DARK UNIVERSE
(2023)
Article
Chemistry, Physical
L. Urban, T. H. Thompson, C. Ochsenfeld
Summary: An empirically scaled version of the MP2-F12 method is introduced, which requires a basis set dependent scaling factor determined by fitting a set of test molecules, and accurately describes a wide range of systems. The new method not only shows remarkably good performance on the S22 and L7 test sets, but also exhibits distinct speedups compared to the unscaled F12 correction for all considered systems.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Article
Materials Science, Multidisciplinary
Yong-Yi Huang
Summary: This paper explains that the canonical transformations in matrix mechanics are actually just transformations of different representations in standard quantum mechanics. It also demonstrates the non-degenerate, degenerate, and time-dependent perturbation theory in matrix mechanics, solving the mystery of time-dependent perturbation theory in this context. Additionally, the Kramers' dispersion formula from time-dependent perturbation theory in matrix mechanics is derived from wave mechanics.
RESULTS IN PHYSICS
(2022)
Article
Engineering, Mechanical
Nidhish Jain, Jongmin Shim
Summary: This study investigates the mechanisms of compression-driven pattern transformations in 2-D soft granular crystals using numerical analysis and model construction. The results show a close relationship between pattern transformations and instability. The study also confirms the effectiveness of the simplified model.
INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES
(2022)
Article
Chemistry, Physical
Hiroshi Nakatsuji, Hiroyuki Nakashima, Yusaku I. Kurokawa
Summary: This paper generalizes the scaling function g for accurate solutions of the Schrodinger equation with the free complement theory. The scaling functions for electron-nuclear and electron-electron interactions are generalized. The conditions for collisional and asymptotic behavior lead to the classification of scaling functions into correct, reasonable, and approximate classes. The accuracy of various electron-electron scaling functions is examined for the helium atom, with the functions produced from the potential operator showing higher importance. The correct-class scaling functions give the most accurate results, while the reasonable-class functions are less accurate.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Chemistry, Multidisciplinary
Julia Kroeger, Filip Podjaski, Goekcen Savasci, Igor Moudrakovski, Alberto Jimenez-Solano, Maxwell W. Terban, Sebastian Bette, Viola Duppel, Markus Joos, Alessandro Senocrate, Robert Dinnebier, Christian Ochsenfeld, Bettina V. Lotsch
Summary: The influence of different counterions on the conductivity and photocatalytic activity of 2D carbon nitride poly(heptazine imide) (PHI) was investigated. Na-PHI showed superior conductivity and photocatalytic activity compared to other M-PHIs, likely due to the geometry and size of the ions in the pores. Increasing relative humidity resulted in significant improvements in both ionic conductivity and photocatalytic activity.
ADVANCED MATERIALS
(2022)
Article
Chemistry, Physical
Michael Glasbrenner, Daniel Graf, Christian Ochsenfeld
Summary: A method for computing NMR shieldings using direct RPA is presented, with accuracy depending on the DFT reference orbitals and amount of Hartree-Fock exchange. Results show that shieldings with Hartree-Fock reference are more accurate than MP2 and comparable to CCSD shieldings. At least triple-zeta basis sets are required for reliable results in basis set convergence analysis.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2022)
Article
Chemistry, Physical
Johannes C. B. Dietschreit, Dennis J. Diestler, Christian Ochsenfeld
Summary: This article discusses the relationship between free energy and energy profiles in chemical reactions, pointing out the misconception of equating the energy profile with the minimum energy path, and elucidating the role of entropy. The article proposes a criterion based on the relationship between free energy and energy profile for selecting collective variables and applies it to a two-dimensional model.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Chemistry, Physical
Andreas Hulm, Johannes C. B. Dietschreit, Christian Ochsenfeld
Summary: The eABF method and its newer variants enable rapid exploration of the configuration space of chemical systems. By using the MBAR method, statistical weights of individual frames can be computed, enhancing the prediction of nuclear magnetic resonance shieldings for ensemble property calculations.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Chemistry, Physical
Y. Lemke, J. Kussmann, C. Ochsenfeld
Summary: Reduced density matrix functional theory (RDMFT) is a promising approach for describing strongly correlated systems, but it is currently limited by its dependence on natural orbitals and the costly construction of two-electron integrals. This work presents efficient integral-direct methods that can be integrated into existing self-consistent energy minimization frameworks, resulting in significant speedups and reduced memory requirements.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2022)
Article
Chemistry, Physical
Felix H. Bangerter, Michael Glasbrenner, Christian Ochsenfeld
Summary: This study employs the tensor-hyper-contracted (THC) method to compute hyperfine coupling constants (HFCCs). By reducing the computational complexity and storage requirements, this method achieves significant improvements in efficiency.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2022)
Article
Chemistry, Physical
Lars Urban, Henryk Laqua, Christian Ochsenfeld
Summary: The utilization of RI-J and snLinK methods accelerates the computation of multiple orbital spaces within the Fock matrix in R12/F12 theory, while maintaining numerical errors below chemical accuracy.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2022)
Article
Chemistry, Medicinal
Carina Glas, Eli Naydenova, Severin Lechner, Nathalie Woessner, Liu Yang, Johannes C. B. Dietschreit, Hongyan Sun, Manfred Jung, Bernhard Kuster, Christian Ochsenfeld, Franz Bracher
Summary: This study developed a new generation of Sirt5 inhibitors that are potent and subtype-selective, with favorable pharmacokinetic properties. The inhibitors showed promising in vitro activities and were found to have no cytotoxicity. Chemoproteomic selectivity profiling confirmed Sirt5 as the main target, further supporting the specificity of these novel inhibitors.
EUROPEAN JOURNAL OF MEDICINAL CHEMISTRY
(2022)
Article
Chemistry, Physical
Johannes C. B. Dietschreit, Dennis J. J. Diestler, Andreas Hulm, Christian Ochsenfeld, Rafael Gomez-Bombarelli
Summary: In this study, we investigated the calculation of activation free energy in chemical reactions and found that the approximation of the free-energy profile can lead to large errors. By defining a new exact expression, we identified an unambiguous method for calculating the activation free energy. The results suggest that this approach has practical value in dealing with high-dimensional potential energy surfaces and selecting appropriate variables.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Chemistry, Physical
F. Sacchetta, D. Graf, H. Laqua, M. A. Ambroise, J. Kussmann, A. Dreuw, C. Ochsenfeld
Summary: This article presents an atomic-orbital reformulation of the coupled cluster model, extending its applicability to molecules with hundreds of atoms and triple-zeta basis sets. The method achieves sub-quadratic computational scaling through sparse linear algebra and an attenuated Coulomb metric, while reducing the prefactor with Cholesky decomposition of the density matrix.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Chemistry, Physical
Alexandra Stan, Beatriz von der Esch, Christian Ochsenfeld
Summary: The nanoreactor approach has the ability to accelerate the discovery of reaction pathways and has a strong predictive power for reactive diversity. By comprehensive study and optimization of simulation parameters, this method can generate precursors for the synthesis of RNA and discover new reaction routes and highly reactive molecules.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2022)
Article
Chemistry, Physical
Henryk Laqua, Johannes C. B. Dietschreit, Jorg Kussmann, Christian Ochsenfeld
Summary: Optimizations targeting the major bottleneck in hybrid Kohn-Sham density functional theory molecular dynamics simulations have been proposed to provide an efficient electronic structure theory method. By avoiding expensive integral evaluations and combining the SCF step with nuclear forces evaluation, the total runtime of AIMD simulations has been reduced by about 25%, leading to improved hardware utilization and overall throughput.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2022)
Article
Chemistry, Physical
Viktoria Drontschenko, Daniel Graf, Henryk Laqua, Christian Ochsenfeld
Summary: A method for evaluating analytical frozen-core gradients within the random phase approximation is presented. The method outlines an efficient way to evaluate the response of the density of active electrons and the response of the standard Kohn-Sham density. By using Cholesky decomposed densities, the method achieves speedups in calculations and shows that the errors introduced by the frozen-core approximation are practically insignificant for molecular geometries.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2022)
Article
Chemistry, Physical
M. A. Ambroise, F. Sacchetta, D. Graf, C. Ochsenfeld, A. Dreuw
Summary: A novel local approach is proposed for the quantum-chemical computation of excited states by extending the atomic-orbital formulation to the second-order algebraic diagrammatic construction scheme using Laplace transform. The CDD-DF-SOS-ADC(2) method achieves substantial reduction in computational effort by exploiting the sparsity of two-electron repulsion integrals, atomic ground-state density matrix, and atomic transition density matrix. It is shown that asymptotically linear scaling can be achieved for linear carboxylic acids, and sub-cubic scaling can be achieved for electron-dense systems with sparse transition density. The memory footprint and accuracy of the method are also explored.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Chemistry, Physical
Johannes C. B. Dietschreit, Beatriz von der Esch, Christian Ochsenfeld
Summary: This study investigates the computational characterization of enzymatic reactions, specifically focusing on the estimation of free energy barriers using QM/MM methods. The authors highlight the challenges in this estimation and propose the use of umbrella sampling to compute the free energy profile of the initial reaction step. The results suggest that the initial step of the deacylation reactions catalyzed by sirtuins follows a conserved S(N)2-type reaction mechanism.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2022)