Article
Physics, Multidisciplinary
Hui Dong, Jun Jiang, Zhongwen Wu, Chenzhong Dong, Gediminas Gaigalas
Summary: A new program for calculating polarizabilities using the fully relativistic multiconfiguration Dirac-Hartree-Fock method has been developed. The program was used to calculate the static electric-dipole polarizabilities of beryllium and determine the blackbody radiation shift of a clock transition, with results in good agreement with other theoretical findings.
Article
Astronomy & Astrophysics
J. Lozano, A. Agadjanov, J. Gegelia, U-G Meissner, A. Rusetsky
Summary: In this study, we calculate the spin-averaged amplitude for doubly virtual forward Compton scattering off nucleons in the framework of manifestly Lorentz-invariant baryon chiral perturbation theory at complete one-loop order O(p(4)), considering both infinite and finite volume cases. The obtained results allow for a detailed estimation of the finite-volume corrections to the amplitude, which can be extracted on the lattice using the background field technique.
Article
Optics
Jesse S. Schelfhout, John J. McFerran
Summary: Relativistic multiconfiguration Dirac-Hartree-Fock calculations were conducted for different states of neutral ytterbium, evaluating mass- and field-shift parameters and hyperfine interaction. Isotope shifts were estimated by multiple means to predict clock-line frequencies, with implications for nonlinear tests and signatures beyond the standard model.
Article
Chemistry, Physical
Chen Zhou, Dihua Wu, Laura Gagliardi, Donald G. Truhlar
Summary: The study demonstrates how spin-orbit coupling can be included in MC-PDFT and applied to the calculation of magnetic g tensors for transition-metal molecules. The MC-PDFT methods are shown to be superior in both accuracy and efficiency compared to complete active space second-order perturbation theory.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2021)
Article
Optics
B. M. Roberts, C. J. Fairhall, J. S. M. Ginges
Summary: Motivated by recent measurements, this study provides a detailed analysis of electric dipole (E1) transition amplitudes in various alkali-metal atoms and alkali-metal-like ions. The high-precision calculations using the correlation potential method demonstrate excellent agreement with experimental determinations and other theoretical evaluations. Moreover, the study extracts high-precision values for several E1 amplitudes through the combination of branching ratio calculations and recent measurements.
Article
Optics
Jesse S. Schelfhout, John J. McFerran
Summary: In this study, multiconfiguration Dirac-Hartree-Fock calculations were performed for neutral cadmium and mercury using the GRASP2018 package. The mass- and field-shift parameters for the S-1(0) - P-3(0)o and S-1(0) - P-3(1)o lines were evaluated. Revised estimates of the nuclear charge parameters and differences in mean-square charge radii were made, and the second-order hyperfine interaction for the P-3(0,1)o levels was examined.
Article
Chemistry, Multidisciplinary
Michael Franz, Frank Neese, Sabine Richert
Summary: This study presents a computational method to determine the excited state exchange couplings in three-electron-three-centre systems. The method is applied to molecules composed of a perylene chromophore and various stable radicals to calculate the exchange interaction between the chromophore and radical. In addition, a method to extract individual exchange interactions and analyze their contributions to the overall exchange interaction is proposed, providing valuable insights for future design optimization.
Article
Chemistry, Physical
Dongbo Zhao, Yilin Zhao, Xin He, Yunzhi Li, Paul W. Ayers, Shubin Liu
Summary: In this study, we demonstrate an efficient and accurate method for predicting the molecular response properties of condensed-phase systems under periodic boundary conditions. By combining the GEBF and ITA approaches, we establish linear relations between small subsystems and larger subsystems, allowing for the direct prediction of polarizabilities from the molecular wavefunction via ITA quantities. The proposed PBC-GEBF-ITA protocol shows good efficiency and transferability for periodic systems with hundreds of atoms in a unit cell.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2023)
Article
Chemistry, Physical
Ernest Opoku, Filip Pawlowski, J. V. Ortiz
Summary: This article introduces a new method for calculating self-energies that surpasses previous methods in terms of accuracy, efficiency, and interpretability. It also presents an improved algorithm to overcome convergence difficulties. Numerical tests show that the new non-diagonal, renormalized methods are slightly more accurate than their diagonal counterparts, but come with increased computational complexity.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Chemistry, Physical
Leonid Shirkov, Michal Tomza
Summary: The isotropic and anisotropic coefficients C-n(l,m) of long-range spherical expansion in the dispersion and induction intermolecular energies are calculated for complexes containing aromatic molecules and alkali or alkaline-earth-metal atoms. The properties of the aromatic molecules and alkali or alkaline-earth-metal atoms are obtained using response theory and analytical wavefunctions. The dispersion and induction coefficients with n > 6 are shown to be important for accurately predicting interaction energy in the van der Waals region at R approximate to 6 A. These long-range potentials are valuable for spectroscopic and scattering studies.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Physics, Applied
Rhona Hamilton, Benjamin M. Roberts, Sarah K. Scholten, Clayton Locke, Andre N. Luiten, Jacinda S. M. Ginges, Christopher Perrella
Summary: The interaction between light and an atom causes perturbations in the atom's energy levels, leading to light shifts. These light shifts affect the accuracy and precision of atomic clocks. A study was conducted on the light shifts and dynamic polarizabilities of a two-photon atomic clock based on the 5S1/2-5D5/2 transition in rubidium-87. Experimental and theoretical values for a magic wavelength in the range of 770-800 nm and the electric dipole (E1) matrix element for the 5P3/2-5D5/2 transition were determined. The study resolved a previous discrepancy between theory and experiment.
PHYSICAL REVIEW APPLIED
(2023)
Article
Chemistry, Physical
Jiayao Li, Qiuyan Feng, Changwei Wang, Yirong Mo
Summary: In this study, the binding energy profiles and bonding nature of counter-intuitive anion coinage bonds (CiBs) were explored by constructing thirty-one complexes and theoretically studying the inter-anion CiBs. The metastability and kinetic stability of these CiBs were supported by potential wells and ab initio molecular dynamics simulations. The importance of the electrostatic interaction and the repulsive factor of Pauli exchange repulsion in the formation and stability of anion pairs were highlighted.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Chemistry, Physical
Bonis Barcza, Adam B. Szirmai, Attila Tajti, John F. Stanton, Peter G. Szalay
Summary: Although Coupled-Cluster methods accurately describe excited electronic states, their computational costs limit their application. This study focuses on fragment-based approaches for noncovalently bound molecular complexes with interacting chromophores. Two approaches were tested for describing the states localized on the fragments with electrostatic interactions, Pauli repulsion, and dispersion effects. The effective fragment potential method was found to provide an adequate correction. Electrostatic contributions were sufficient for modeling the interaction of the localized chromophores.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2023)
Article
Optics
Ravi Kumar, S. Chattopadhyay, D. Angom, B. K. Mani
Summary: In this study, relativistic coupled-cluster theory was used to calculate the electric dipole polarizability and electron correlation energy of superheavy elements. The results showed that the main contribution comes from valence electrons, while contributions from interactions and corrections varied with the Z value.
Article
Chemistry, Physical
Laura C. Motta, Jochen Autschbach
Summary: A study was conducted on a large set of neptunium compounds with different oxidation states to investigate the Mossbauer isomer shift. The study used wave function calculations and density matrix renormalization group algorithms to understand covalency in f-elements complexes. The researchers found that the calculations produced different orbital overlocalization errors for low and high Np oxidation states. Attempts to mitigate the errors using large active spaces were only partially successful, highlighting the need for explicit treatment of dynamic correlation. CASPT2 calculations performed well, and a rational active space selection proved beneficial for determining the optimal reference wave function.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2022)
