Article
Chemistry, Physical
Miria C. dos Santos, Francielly T. Souto, Celso R. Nicoleti, Matheus C. Colaco, Giovanni F. Caramori, Vanderlei G. Machado
Summary: Brooker's merocyanine (BM) is a solvatochromic probe with a band in the visible region sensitive to changes in polarity. Inspired by BM, we synthesized four novel dipodal and tripodal solvatochromic dyes (1b-4b) and characterized them using spectroscopic and calorimetric techniques. The dyes showed negative solvatochromism, exhibiting different colors with changes in solvent polarity. Different parameter strategies fitted the experimental data, with HBD acidity of the solvent playing a major role in solvation. Theoretical calculations revealed that the absorption bands in the dyes were due to a π → π* transition, but did not reproduce the experimentally observed negative solvatochromism. Comparing the experimental and theoretical data with literature provided valuable information.
JOURNAL OF MOLECULAR LIQUIDS
(2023)
Article
Chemistry, Physical
Tanner Culpitt, Laurens D. M. Peters, Erik I. Tellgren, Trygve Helgaker
Summary: The study investigates the properties of the diagonal nonadiabatic term in the Born-Oppenheimer wave function ansatz, deriving analytic expressions for the Berry curvature and DBOC and calculating their properties in several molecules based on magnetic field strength and bond distance. The results indicate that the characteristics of DBOC and Berry curvature vary between molecules and instances of broken time-reversal symmetry are identified in the dissociation curves of BH and CH+.
JOURNAL OF CHEMICAL PHYSICS
(2022)
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
Physics, Multidisciplinary
Denghong Zhang, Fangjun Zhang, Xiaobin Ding, Chenzhong Dong
Summary: The mass- and field-shift parameters of the 2s S-2(1/2) -> 2p P-2(1/2,3/2) transitions in Li-like Ca ions were calculated using MCDHF and RCI methods, showing that the mass shift is greater than the field shift.
Article
Chemistry, Physical
Siriluk Kanchanakungwankul, Donald G. Truhlar
Summary: The study compared the accuracy of several long-range-corrected hybrid meta functionals, with the results showing that Minnesota LC-hybrid meta functionals have the smallest mean absolute deviation in the ionization energy theorem VIE test, while the LC-omega HPBE functional also performed well in this regard.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2021)
Article
Chemistry, Physical
M. Diop, M. El-Hayek, J. Attard, A. Muhieddine, V. Veremeienko, S. Soorkia, Ph. Carbonniere, A. de la Lande, B. Soep, N. Shafizadeh
Summary: In this study, the properties of Pheophytin a and chlorophyll a in photosynthesis were investigated using mass spectrometry. The results showed that both Pheophytin and chlorophyll were detected intensively in the protonated mode, with their main fragmentation route being the loss of the phytyl chain. In the negative mode, Pheophytin remained intact, while chlorophyll was not detected under normal conditions. The addition of methanol solvent molecule facilitated the detection of chlorophyll. Computational and experimental results indicated that the addition of methanol occurred on a double bond of deprotonated chlorophyll.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Chemistry, Physical
William Dawson, Eisuke Kawashima, Laura E. Ratcliff, Muneaki Kamiya, Luigi Genovese, Takahito Nakajima
Summary: In this study, we present recent developments of the NTChem program for large scale hybrid density functional theory calculations on the supercomputer Fugaku. We combine these developments with a complexity reduction framework to assess the impact of basis set and functional choice on fragment quality and interaction. Furthermore, we utilize the all electron representation to study system fragmentation in different energy envelopes. Based on this analysis, we propose two algorithms for computing the orbital energies of the Kohn-Sham Hamiltonian, which can efficiently be applied to systems composed of thousands of atoms and reveal the origin of spectral properties.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Chemistry, Physical
Sheng Chen, Kai Wu, Wei Hu, Jinlong Yang
Summary: In this study, the ACE-ISDF formulation is derived for hybrid functional calculations in unrestricted and noncollinear spin DFT with plane waves and periodic boundary conditions. Improved ACE-ISDF low-rank approximations are proposed to further reduce the computational cost for spin-noncollinear systems. Numerical results demonstrate the efficiency and accuracy of the ACE-ISDF method in investigating the electronic and magnetic properties of periodic magnetic systems.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Chemistry, Physical
Hideaki Takahashi
Summary: This work focuses on the development of a nonlocal kinetic-energy functional based on the response function for molecular systems, which enables the use of orbital-free density-functional theory (OF-DFT) in the hybrid QM/MM method. It differs from previous functionals that rely on the homogeneous electron gas as a reference for the response function. Benchmark tests on a QM water molecule in a dimer system and in a condensed environment show that our approach can adequately reproduce the energetics and polarization density of the QM solute under the influence of the MM environment. This suggests the potential ability of the kinetic-energy functional based on response functions for molecular reference systems.
JOURNAL OF CHEMICAL PHYSICS
(2023)
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, Physical
Tim Gould, Zahed Hashimi, Leeor Kronik, Stephen G. Dale
Summary: In this paper, a simple correction method based on rigorous ensemble density functional theory is introduced, which makes the HOMO-LUMO gap exact in principle and significantly improves accuracy in practice. The method predicts different values for singlet-singlet and singlet-triplet excitations, and the quality of excitation energies is similar to time-dependent density functional theory.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2022)
Article
Chemistry, Physical
Jacques K. Desmarais, Alessandro De Frenza, Alessandro Erba
Summary: A computational procedure is proposed for efficient calculation of derivatives of integrals over non-separable Gaussian-type basis functions in quantum-mechanical simulations. The approach utilizes symbolic computation and automated generation of optimized subroutines to take advantage of sparsity. Implementation in the Crystal code demonstrates considerably improved computational efficiency for energy derivatives with respect to nuclear displacements and lattice parameters.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Chemistry, Multidisciplinary
Aritra Rajak, Ajeet Kumar Singh, Lisa Roy, Anindita Das
Summary: In this study, the self-assembly of a merocyanine dye into higher aggregates in aqueous medium was investigated, revealing the synergistic effect of dipole-dipole interactions and strong dispersion forces.
Article
Chemistry, Physical
Artem Mitrofanov, Nikolai Andreadi, Vadim Korolev, Stepan Kalmykov
Summary: Actinide chemistry often faces limitations with modern theoretical tools due to high computational costs and relativistic effects. The novel relPBE functional serves as an actinide-fitted version of the PBE0 functional, offering an alternative computational approach.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Article
Chemistry, Physical
A. K. Zhuravlev
Summary: This article considers the problem of constructing a guaranteed convergent sequence of corrections to the Hartree-Fock ground state energy of a molecule without storing the many-electron wave function. Several methods based on cumulants are considered, and it is shown that such a sequence can be obtained through Lanczos tridiagonalization, in which the elements of the tridiagonal matrix are calculated through cumulants.
COMPUTATIONAL AND THEORETICAL CHEMISTRY
(2022)