Jahn-Teller and pseudo-Jahn-Teller effects on the vibronic structure of the photoionized spectrum of cyanopropyne.

Nonadiabatic quantum dynamics are carried out to illustrate the photoionized spectrum of the cyanopropyne (CH3-C≡C-C≡N) as reported in recent experimental measurements [Lamarre et al., J. Mol.

Confinement Effects of Two-Dimensional Surfaces on Water Adsorption and Dissociation over Pt(111).

It has been established that the confined space created by stacking a two dimensional (2D) surface atop a metal catalyst serves as a nano-reactor. According to recent research, when a graphene (Gr) overlayer encloses a catalyst from above, the activation barrier for the water dissociation reaction, a process with major industrial significance, decreases. In order to investigate how the effect of confinement varies among different two-dimensional (2D) materials, we study the adsorption and dissociation barriers of water molecule on (111) under graphene, hexagonal boron nitride (h-BN), and heptazine-based graphitic carbon nitride (g-CN) layers using density functional theory calculations.

Efficient Control of Electron Localization and Probability Modulation with Synthesized Two-Color Intense Laser Pulses.

A coupled electron-nuclear dynamical study at attosecond time scale is performed on the HD and H molecular ions under the influence of synthesized intense two-color electric fields. We have employed ω - 2ω and also, ω - 3ω two-color fields in the infrared/mid-infrared regime to study the different fragmentation processes originating from the interference of - ( + ) ( = 1, 2) photon absorption pathways. The branching ratios corresponding to different photofragments are controlled by tuning the relative phase as well as intensity of the two-color pulses, while the effect of the initial nuclear wave function is also studied by taking an individual vibrational eigenstate or a coherent superposition of several eigenstates of HD and H.

Strong Laser Field-Driven Coupled Electron-Nuclear Dynamics: Quantum vs Classical Description.

We have performed a coupled electron-nuclear dynamics study of H molecular ions under the influence of an intense few-cycle 4.5 fs laser pulse with an intensity of 4 × 10 W/cm and a central wavelength of 750 nm. Both quantum and classical dynamical methods are employed in the exact similar initial conditions with the aim of head-to-head comparison of two methodologies.

Bicyclic (alkyl)(amino)carbene (BICAAC) in a dual role: activation of primary amides and CO towards catalytic -methylation.

Herein, we report the first catalytic methylation of primary amides using CO as a C1 source. A bicyclic (alkyl)(amino)carbene (BICAAC) exhibits dual role by activating both primary amide and CO to carry out this catalytic transformation which enables the formation of a new C-N bond in the presence of pinacolborane. This protocol was applicable to a wide range of substrate scopes, including aromatic, heteroaromatic, and aliphatic amides.

Theoretical Chemistry Symposium 2021.

The editorial paints a brief history of the conference - Theoretical Chemistry Symposium, organized by eminent theoretical and computational chemists from India.

Effect of temperature on CO oxidation over Pt(111) in two-dimensional confinement.

Confined catalysis between a two-dimensional (2D) cover and metal surfaces has provided a unique environment with enhanced activity compared to uncovered metal surfaces. Within this 2D confinement, weakened adsorption and lowered activation energies were observed using surface science experiments and density functional theory (DFT) calculations. Computationally, the role of electronic and mechanical factors responsible for the improved activity was deduced only from static DFT calculations.

Dissociative ionization of the H molecule under a strong elliptically polarized laser field: carrier-envelope phase and orientation effect.

A coupled electron-nuclear dynamical study is performed to investigate the sub-cycle dissociation and ionization of the H molecule in a strong 750 nm 4.5 fs elliptically polarized laser pulse. A quasi-classical method is employed in which additional momentum-dependent potentials are added to the molecular Hamiltonian to account for the non-classical effects.

Mode selective chemistry for the dissociation of methane on efficient Ni/Pt-bimetallic alloy catalysts.

The mode selectivity of methane dissociation is studied on three different Ni/Pt-bimetallic alloy surfaces using a fully quantum approach based on reaction path Hamiltonian. Dissociative sticking probability depends on the composition of alloying metals, excited vibrational mode, and symmetry of the reaction path about the plane perpendicular to the catalyst surface containing the carbon atom and two hydrogen atoms. Our calculations show that symmetry of the minimum energy reaction path depends on the surface alloy composition.

Oxygen-Induced Dissociation of a Single Water Molecule in Confined 2-D Layers: A Semiempirical Study.

Semiempirical quantum mechanical methods provide a middle ground to molecule-surface interactions between computationally demanding full ab initio quantum chemistry calculations and force-field calculations. In the present study, the PM7 semiempirical method is used to evaluate the adsorption energy values of X@h-BN monolayer [X=O, OH, and H O], followed by a mechanistic study of oxygen-induced water dissociation on a free-standing h-BN monolayer. Based on oxygen adsorption configurations, two reaction pathways for water dissociation are studied that yield two distinct configurations of double OH-functionalized h-BN monolayer.

Bicyclic (alkyl)(amino)carbene (BICAAC) as a metal-free catalyst for reduction of nitriles to amines.

Bicyclic (alkyl)(amino)carbene (BICAAC) is introduced as a metal-free catalyst for the reduction of various nitriles to the corresponding amine hydrochloride salts in the presence of pinacolborane. Mechanistic investigations combining experiments and DFT calculations suggest a B-H addition to the carbene center, which acts as a carrier of the hydride source.

Spatial and temporal variation of the ambient noise environment of the Sikkim Himalaya.

Ambient noise characteristics are perused to assess the station performance of 27 newly constructed broadband seismic stations across Sikkim Himalaya and adjoining Himalayan foreland basin, installed to study the seismogenesis and subsurface structure of the region. Power spectral densities obtained at each station, compared against the global noise limits, reveal that observed vertical component noise levels are within the defined global limits. However, the horizontal components marginally overshoot the limits due to the tilt effect.

Schematic Design of Metal-Free NHC-Mediated Sequestering and Complete Conversion of SO to Thiocarbonyl -Oxide Derivatives at Room Temperature.

The sequestering and complete conversion of SO to valuable chemicals in a metal-free pathway is highly demanded. The recent success of SO fixation by N-heterocyclic carbenes instigated further studies in this regard. Previous reports were confined within the carbene-SO reaction mechanism and the stability of oxathiirane -oxide derivatives.

Biochar-Supported TiO-Based Nanocomposites for the Photocatalytic Degradation of Sulfamethoxazole in Water-A Review.

Sulfamethoxazole (SMX) is a frequently used antibiotic for the treatment of urinary tract, respiratory, and intestinal infections and as a supplement in livestock or fishery farming to boost production. The release of SMX into the environment can lead to the development of antibiotic resistance among the microbial community, which can lead to frequent clinical infections. SMX removal from water is usually done through advanced treatment processes, such as adsorption, photocatalytic oxidation, and biodegradation.

Competitive Reactivity of SO and NO with -Heterocyclic Carbene: A Mechanistic Study.

Recent DFT based molecular engineering to obtain stable oxathiirane -oxide derivatives evokes the recommencement of the use of carbenes for the sequestering of SO, which has been kept separate so far. Carbene is one of the key chemicals for the sequestering of various premier greenhouse gases like CO, CO, NO, etc. In this respect, a comparative study of the reactivity of carbenes with variant greenhouse gases is highly demanding.

Controlling the Ultrafast Dynamics of HD by the Carrier-Envelope Phases of an Ultrashort Laser Pulse: A Quasi-Classical Dynamics Study.

A theoretical study on the coupled electron-nuclear dynamics of HD molecular ions under ultrashort, intense laser pulses is performed by employing a well-established quasi-classical model. The influence of the laser carrier-envelope phase on various channel (H + D, D + H, and H + D) probabilities is investigated at different laser field intensities. The carrier-envelope phase is found to govern the dissociation (H + D and D + H) and Coulomb explosion (H + D) channel probabilities.

Controlling Chemical Reactions with Laser Pulses.

One of the holy grails of contemporary science is to understand and manipulate chemical reactions to obtain desired products preferentially. To achieve this goal, chemists traditionally choose the correct starting materials and reaction conditions, but it often lacks selectivity and efficiency. A promising alternative is to design laser control schemes and apply them to guide and control chemical reactions.

DFT based engineering of N-heterocyclic carbenes to exacerbate its activity for SO fixation and storage.

Carbene compounds are very reactive to SO which assert their candidature to seize this greenhouse gas. Unfortunately, most of the carbenes which produce S,S-dioxide with SO, undergo dissociation to yield ketone derivative and SO through an intermediate formation of oxathiirane S-oxide derivative. Thus, carbenes are excluded from the list of catalyst for SO fixation and storage technology.

Effect of Intrinsic Properties of Anions on the Electrocatalytic Activity of NiCoO and NiCoO S Grown by Chemical Bath Deposition.

Electrochemical water (HO) splitting is one of the most promising technologies for energy storage by hydrogen (H) generation but suffers from the requirement of high overpotential in the anodic half-reaction (oxygen evolution), which is a four-electron process. Though transition-metal oxides and oxysulfides are increasingly researched and used as oxygen evolution electrocatalysts, the bases of their differential activities are not properly understood. In this article, we have synthesized NiCoO and NiCoO S by a chemical bath deposition technique, and the latter has shown better oxygen evolution performance, both in terms of stability and activity, under alkaline conditions.

Assessment of groundwater geochemistry and diffusion of hexavalent chromium contamination in an industrial town of Italy.

Groundwater contamination by hexavalent chromium (Cr (VI)) is currently a very serious and challenging issue. Therefore, in the present study, 108 shallow groundwater samples were collected during the years 2012 to 2015 (n = 27 samples each year) from an industrial town (Aosta) to assess the contamination status of the area. To evaluate the Cr (VI) concentration level, sources of pollutants and groundwater geochemistry of the study area, a combined approach of the multi-statistical and hydrogeochemical techniques were used.

Evaluation of groundwater salinization and pollution level on Favignana Island, Italy.

Fifty-six groundwater samples were taken from the island of Favignana to evaluate the interaction between the groundwater and seawater, as well as the deterioration factors for the aquifers, using the combined hydrogeochemical and multivariate statistical approaches. Results show that the order of the groundwater chemistry in the study area was Na> Ca>Mg>K and Cl>HCO>SO>NO. The groundwater samples were in the moderate saline zone to highly saline zone and indicate that the groundwater of the island of Favignana was recharged with seawater.

Controlling Electron Dynamics with Carrier-Envelope Phases of a Laser Pulse.

A theoretical study on the ionization dynamics of carbon atom irradiated with a few-cycle, intense laser field is performed within a quasiclassical model to get mechanistic insights into an earlier reported carrier-envelope phase dependency of ionization probabilities of an atom [ Phys. Rev. Lett.

Effects of alloying on mode-selectivity in HO dissociation on Cu/Ni bimetallic surfaces.

The influence of alloying on mode-selectivity in HO dissociation on Cu/Ni bimetallic surfaces has been studied using a fully quantum approach based on reaction path Hamiltonian. Both the metal alloy catalyst surface and the normal modes of HO impact the chemical reactivity of HO dissociation. A combination of these two different factors will enhance their influence reasonably.

HOD on Ni(111): molecular dynamics prediction of molecular beam experiments.

The dissociation of water on a transition-metal catalyst is a fundamental step in relevant industrial processes such as the water-gas shift reaction and steam reforming. Although many theoretical studies have been performed, quantitative agreement between theoretical simulations and molecular beam experiments has not yet been achieved. In this work, we present a predictive molecular dynamics study on the dissociation of mono-deuterated water (HOD) on Ni(111).

Controlling Heterogeneous Catalysis of Water Dissociation Using Cu-Ni Bimetallic Alloy Surfaces: A Quantum Dynamics Study.

Copper-Nickel bimetallic alloys are emerging heterogeneous catalysts for water dissociation which is the rate-determining step of the industrially important water gas shift (WGS) reaction. Yet, the detailed quantum dynamics studies of water-surface scattering in the literature are limited to pure metal surfaces. We present here a three-dimensional wave packet dynamics study of water dissociation on Cu-Ni alloy surfaces, using a pseudodiatomic model of water on a London-Eyring-Polanyi-Sato (LEPS) potential energy surface in order to study the effect of initial vibration, rotation, and orientation of the water molecule on the reactivity.