Journal of Chemical Physics最新文献

The ladder-type population transfer of the HF molecule steered by four-color harmonic laser pulses (HLPs) is investigated using the time-dependent quantum wave packet method. It is found that although there exist large background excitations and many (resonant) transition pathways during the driving, nearly 100% of the population could be transferred to the target state. In particular, such a process could be coherently controlled by changing the phases of the four HLPs, especially the phases of the fundamental and second HLPs, which can be accounted for in large part by the combined effects of the corresponding transition pathways and the maximal amplitude of the total electric field. However, for manipulating the phases of the third and fourth HLPs, both the changes in the maximal electric field amplitude and the asymmetry size fail to guide the variation of the target-state population because of the correlated effects of all these transition pathways, particularly the ones that do not contain the third and fourth HLP excitations. Importantly, our results also denote that the variation of the maximal electric field amplitude may give a well qualitative prediction about the phase-controlled population when the manipulated phase is directly related to all the transition pathways, which is the general case in the widely used two-color scheme. In addition, the maximal amplitude of the total electric field tends to play a more important role than its asymmetry size in the phase-controlled population transfer process.

We present the theory and implementation of a relativistic third-order algebraic diagrammatic construction [ADC(3)] method based on a four-component (4c) Dirac-Coulomb Hamiltonian for the calculation of ionization potentials (IPs), electron affinities (EAs), and excitation energies (EEs). Benchmarking calculations for IP, EA, and EE were performed on both atomic and molecular systems to assess the accuracy of the newly developed four-component relativistic ADC(3) method. The results show good agreement with the available experimental data. The Hermitian nature of the 4c-ADC(3) Hamiltonian, combined with the perturbative truncation of the wave function, offers significant computational advantages over the standard equation-of-motion coupled-cluster approach, particularly for property calculations. The method's suitability for property calculations is further demonstrated by computing oscillator strengths and excited-state dipole moments for heavy elements.

We propose an accurate method for evaluating temperature and pressure in Langevin integration, based on the approach by Leimkuhler and Matthews (J. Chem. Phys. 138, 174102). This method improves the quality of configuration space than other Langevin dynamics methods. However, it encounters issues in pressure evaluation due to inaccuracies in momentum space. In particular, the conventional approach for calculating kinetic temperature using the full-time step momentum introduces errors proportional to the square of the time step (Δt2), leading to unreliable results when employing a large time step under isothermal-isobaric conditions. By calculating kinetic energy using the half-time step momentum in pressure evaluation, we can reduce the numerical errors. We performed molecular dynamics (MD) simulations using our refined pressure evaluation and improved accuracy and stability in the isothermal-isobaric MD simulations even with a long time step (Δt = 5 fs).

We present a comprehensive quantum mechanical study of stereodynamic control of HD + He and D2 + He collisions that have been probed experimentally by Perreault et al. [J. Phys. Chem. Lett. 13, 10912 (2022)] using Stark-induced adiabatic Raman passage (SARP) techniques. Our calculations utilize a highly accurate full-dimensional H2 + He interaction potential with diagonal Born-Oppenheimer correction appropriate for HD and D2 isotopomers. The results show that rotational quenching of HD from j = 2 → j' = 0 in v = 2, j = 2 → j' = 1 in v = 2 and v = 4, and j = 4 → j' = 3 in v = 4 is dominated by an l = 1 shape resonance located between 0.1 and 1.0 cm-1. For collision energies less than 0.1 cm-1, isotropic scattering prevails. An l = 1 resonance centered around 0.02 cm-1 is also found to dominate the j = 2 → j' = 0 and j = 4 → j' = 2 transitions in v = 4 for He-D2 collisions consistent with our prior studies of Δj = -2 transition in He + D2(v = 2, j = 2) collisions. Our analysis does not support the hypothesis of Perreault et al. [J. Phys. Chem. Lett. 13, 10912 (2022)] that a strong l = 2 resonance controls the angular distribution for Δj = -2 transition for both systems. Despite improvements in the development of the potential energy surface, a good agreement with SARP experiments for v = 2 is achieved only when contributions from collision energies less than 1.0 cm-1 were excluded in the computation of velocity averaged differential rate coefficients for both systems. This could be due to some uncertainties in the velocity spread in the experiment that employs co-propagation of the collision partners and possibly, the neglect of transverse velocities in the simulation of the experiment.

Vacuum polarization (VP) and electron self-energy (SE) are implemented and evaluated as quantum electrodynamic (QED) corrections in a (quasi-relativistic) two-component zeroth order regular approximation (ZORA) framework. For VP, the Uehling potential is considered, and for SE, the effective potentials proposed by Flambaum and Ginges as well as the one proposed by Pyykkö and Zhao. QED contributions to ionization energies of various atoms and group 2 monofluorides, group 1 and 11 valence orbital energies, 2P1/2 ← 2S1/2 and 2P3/2 ← 2S1/2 transition energies of Li-, Na-, and Cu-like ions of nuclear charge Z = 10, 20, …, 90 as well as Π1/2 ← Σ1/2 and Π3/2 ← Σ1/2 transition energies of BaF and RaF are presented. Furthermore, perturbative and self-consistent treatments of QED corrections are compared for Kohn-Sham orbital energies of gold. It is demonstrated that QED corrections can be obtained in a two-component ZORA framework efficiently and in excellent agreement with corresponding four-component results.

The benchmark theory of hydration forces that relies on the phenomenological expressions developed by Marčelja and Radić (MR) has recently been revived by experimental, computational, and theoretical advances. Here, we consider the effect of surface polarization on electrolytes in a slab geometry by combining the MR approach to polarization with Poisson-Boltzmann theory. Due to the coupling of bulk and surface fields, not only is the electrostatics modified by polarization, but maybe even more importantly, vice versa: a finite polarization at the wall is sufficient to generate a finite electrostatic potential even in the absence of net charges on the wall. We determine the polarization and electrostatic potential profiles and the free energy of the system. Our results show that the presence of surface polarization alone suffices to imprint the bulk structural properties on the electrostatic field in an electrolyte.

Intermolecular charge-transfer (xCT) excited states important for various practical applications are challenging for many standard computational methods. It is highly desirable to have an affordable method that can treat xCT states accurately. In the present work, we extend our self-consistent perturbation methods, named one-body second-order Møller-Plesset and its spin-opposite scaling variant (O2BMP2), for excited states without additional costs to the ground state. We then assessed their performance for the prediction of xCT excitation energies. Thanks to self-consistency, our methods yield small errors relative to high-level coupled cluster methods and outperform other same scaling (N5) methods, such as CC2 and ADC(2). In particular, O2BMP2, whose scaling can be reduced to N4, can even reach the accuracy of CC3 (N7) with errors less than 0.1 eV. This method is thus highly promising for treating xCT states in large compounds vital for applications.

We consider the quantum dynamics of a pair of coupled quantum oscillators coupled to a common correlated dissipative environment. The resulting equations of motion for both the operator moments and covariances can be integrated analytically using the Lyapunov equations. We find that for fully correlated and fully anti-correlated environments, the oscillators relax into a phase-synchronized state that persists for long-times when the two oscillators are nearly resonant and (essentially) forever if the two oscillators are in resonance. We identify an exceptional point that indicates the onset of broken symmetry between an unsynchronized and synchronized dynamical phase of the system as correlations within the environment are increased. We also show that the environmental noise correlation leads to quantum entanglement, and all the correlations between the two oscillators are purely quantum mechanical in origin. This work provides a robust mathematical foundation for understanding how long-lived exciton coherences can be linked to vibronic correlation effects.

The nucleosome serves as the fundamental unit of chromatin organization, with electrostatic interactions acting as the driving forces in the folding of nucleosomes into chromatin. Perturbations around physiological pH conditions can lead to changes in the protonation states of titratable histone residues, impacting nucleosome surface electrostatic potentials and interactions. However, the effects of proton uptake or release of histone ionizable groups on nucleosome-partner protein interactions and higher-order chromatin structures remain largely unexplored. Here, we conducted comprehensive analyses of histone titratable residue pKa values in various nucleosome contexts, utilizing 96 experimentally determined complex structures. We revealed that pH-induced changes in histone residue protonation states modulated nucleosome surface electrostatic potentials and significantly influenced nucleosome-partner protein interactions. Furthermore, we observed that proton uptake or release often accompanied nucleosome-partner protein interactions, facilitating their binding processes. In addition, our findings suggest that alterations in histone protonation can also regulate nucleosome self-association, thereby modulating the organization and dynamics of higher-order chromatin structure. This study advances our understanding of nucleosome-chromatin factor interactions and how chromatin organization is regulated at the molecular level.

On the basis of recent advancements in the Hamiltonian matrix density functional for multiple electronic eigenstates, this study delves into the mathematical foundation of the multistate density functional theory (MSDFT). We extend a number of physical concepts at the core of Kohn-Sham DFT, such as density representability, to the matrix density functional. In this work, we establish the existence of the universal matrix functional for many states as a proper generalization of the Lieb universal functional for the ground state. Consequently, the variation principle of MSDFT can be rigorously defined within an appropriate domain of matrix densities, thereby providing a solid framework for DFT of both the ground state and excited states. We further show that the analytical structure of the Hamiltonian matrix functional is considerably constrained by the subspace symmetry and invariance properties, requiring and ensuring that all elements of the Hamiltonian matrix functional are variationally optimized in a coherent manner until the Hamiltonian matrix within the subspace spanned by the lowest eigenstates is obtained. This work solidifies the theoretical foundation to treat multiple electronic states using density functional theory.