Physical Chemistry Chemical Physics

doi: 10.1039/d5cp90034dpmid: N/A

doi: 10.1039/d5cp90035bpmid: N/A

doi: 10.1039/d5cp90036kpmid: N/A

Bondar, Ana-Nicoleta; Brown, Leonid S.; Kandori, Hideki; Ladizhansky, Vladimir

doi: 10.1039/d4cp90218apmid: 39873462

Guest editors Ana-Nicoleta Bondar, Leonid S. Brown, Hideki Kandori and Vladimir Ladizhansky introduce this themed collection celebrating the research of Prof. Judith Herzfeld.

Park, Jae Woo

doi: 10.1039/d4cp03671apmid: 39895376

Electron correlations should be appropriately included in quantum chemistry calculations to accurately describe the energy and wave functions. In multiconfigurational methods, the reference functions are written as linear combinations of multiple electronic configurations to describe static correlations. Using the multiconfigurational reference functions, it is also possible to correct for dynamical correlations using various methods. Geometry optimizations and dynamics simulations are among the most prominent applications of quantum chemistry methods. Such applications become much more straightforward when analytical nuclear gradients are available. Many efficient algorithms for computing analytical nuclear gradients and derivative coupling using multireference perturbation theories (MRPTs) have recently been developed. This work aims to provide a comprehensive and easy-to-follow review of analytical gradient theories and the properties of methods for obtaining analytical gradients and derivative coupling methods using MRPTs. We also briefly review the practical applications of these methods in performing nonadiabatic dynamics simulations.

Fthenakis, Zacharias G.; Menon, Madhu

doi: 10.1039/d4cp04258apmid: 39903504

Using ab initio methods we show that by applying shear strain, a phase transition occurs between the AB and the AA Si2BN planar sheets. Si–Si bonds stretch and bend towards the strain direction, causing an internal displacement of the remaining almost unchanged Si2BN strips. As the shear strain increases, Si–Si bonds weaken and break, while leading to new Si–Si bond formation and causing the phase transition. The planar structure is maintained throughout the application of the strain, with no buckling, a phenomenon not reported so far in other 2D materials. Performing the same calculations for graphene we show that its structural deformations are strikingly different and result in buckling.

Malkina, Olga L.; Bűhl, Michael; Chalmers, Brian A.; Komorovsky, S.

doi: 10.1039/d4cp04594gpmid: 39878026

The solvent effect on the indirect 1J(M–P) spin–spin coupling constant in phosphine selenoether peri-substituted acenaphthene complexes LMCl2 is studied at the PP86 level of nonrelativistic and four-component relativistic density functional theory. Depending on the metal, the solvent effect can amount to as much as 50% or more of the total J-value. This explains the previously found disagreement between the 1J(Hg–P) coupling in LHgCl2, observed experimentally and calculated without considering solvent effects. To address the solvent effect, we have used polarizable continuum and microsolvated models. The solvent effect can be separated into indirect (structural changes) and direct (changes in the electronic structure). These effects are additive, each brings roughly about 50% of the total effect. For the in-depth analysis, we use a model with a lighter metal, Zn, instead of Hg. A much smaller solvent effect on 1J(Hg–P) for a dimer form of LHgCl2 is explained. Pilot calculations of 1J(M–P) couplings in analogous systems with other metals indicate that for metals preferring square planar structures the solvent effect is insignificant because these structures are fairly rigid. Tetrahedral structures are less constrained and can respond more easily to external effects such as solvation.

Rodríguez-Kessler, Peter L.; Muñoz-Castro, Alvaro

doi: 10.1039/d4cp04444dpmid: 39887704

In this work, we employ density functional theory (DFT) to explore the structure of boron clusters doped with two zinc atoms (B7Zn2 or Zn2B7). The results show that the most stable structure is a Zn2 motif standing over a B7 wheel, which is 0.89 eV lower in energy compared to the classical inverse-sandwich structure for B7TM2 (TM = transition metal) clusters. The characteristics of these systems are evaluated by the IR spectra to guide plausible experimental realization. In addition, density of states, and bonding characteristics were evaluated. Our results denote the formation of an intermediate Zn–Zn bond order given by the key electron-acceptor nature of the B7 motif, leading to a depopulation of antibonding Zn–Zn orbitals and population of the respective bonding orbitals. Thus, the evaluation and use of more electron-deficient supporting ligands may trigger a quest for the design of plausible structures featuring larger Zn–Zn elusive bond orders in stable species.

Tripathi, Divya; Pyla, Maneesh; Dutta, Achintya Kumar; Matsika, Spiridoula

doi: 10.1039/d4cp04333bpmid: 39903129

Interactions of low-energy electrons with the DNA and RNA nucleobases are known to form metastable states, known as electronic resonances. In this work, we study electron attachment to solvated uracil, an RNA nucleobase, using the orbital stabilization method at the Equation of Motion-Coupled Cluster for Electron Affinities with Singles and Doubles (EOM-EA-CCSD) level of theory with the Effective Fragment Potential (EFP) solvation method. We benchmarked the approach using multireference methods, as well as by comparing EFP and full quantum calculations. The impact of solvation on the first one particle (1p) shape resonance, formed by electron attachment to the π* LUMO orbital, as well as the first two particle one hole (2p1h) resonance, formed by electron attachment to neutral uracil's π–π* excited state, was investigated. We used molecular dynamics simulations for solvent configurations and applied charge stabilization technique-based biased sampling to procure configurations adequate to cover the entire range of the electron attachment energy distribution. The electron attachment energy in solution is found to be distributed over a wide range of energies, between 4.6 eV to 6.8 eV for the 2p1h resonance, and between −0.1 eV to 2 eV for the 1p resonance. The solvent effects were similar for the two resonances, indicating that the exact electron density of the state is not as important as the solvent configurations. Multireference calculations extended the findings showing that solvation effects are similar for the lowest four resonances, further indicating that the specific solute electron density is not as important, but rather the water configurations play the most important role in solvation effects. Finally, by comparing bulk solvation to clusters of uracil with a few water molecules around it, we find that the impact of microsolvation is very different from that of bulk solvation.

Abdel-Hameed, Reda; Elnouby, Mohamed S.; Zahran, Hoda F.; Abu-Rashed, Nagah; Ashmawy, Ashraf; Ali, Eshraqa; Huwaimel, Bader; Abdallah, M.; Alanazi, Kaseb D.; Kamoun, Elbadawy A.; Younes, Sara M.

doi: