Vertical Ionization Research Articles

Dissociation and Isomerization Following Ionization of Ethylene: Insights from Nonadiabatic Dynamics Simulations.

Photoionized and electronically excited ethylene C2H4+ can undergo H-loss, H2-loss, and ethylene-ethylidene isomerization, where the latter entails a hydrogen migration. Recent pioneering experiments with few-femtosecond extreme ultraviolet pulses and complementary theoretical studies have shed light on the photodynamics of this prototypical organic cation. However, no theoretical investigation based on dynamics simulations reported to date has described the mechanisms and time scales of dissociation and isomerization. Herein, we simulate the coupled electron-nuclear dynamics of ethylene following vertical ionization and electronic excitation to its four lowest-lying cationic states. The electronic structure is treated at the CASSCF level, with an active space large enough to describe bond breaking and formation. The simulations indicate that dissociation and isomerization take place mainly on the cationic ground state and allow the probing of previous hypotheses concerning the correlation between the photochemical outcome and the traversed conical intersections. The results, moreover, support the long-standing view that H2-loss may occur from the ethylidene form. However, the ethylene-ethylidene isomerization time predicted by the simulations is considerably longer than those previously inferred from indirect experimental measurements.

Valence photoelectron imaging of molecular oxybenzone.

An oxybenzone molecule in the gas phase was characterized by mass spectrometry and angle-resolved photoelectron spectroscopy, using both single and multiphoton ionization schemes. A tabletop high harmonic generation source with a monochromator was used for single-photon ionization of oxybenzone with photon energies of up to 35.7 eV. From this, vertical ionization and appearance energies, as well as energy-dependent anisotropy parameters were retrieved and compared with the results from DFT calculations. For two-photon ionization using 4.7 eV light, we found a higher appearance energy than in the extreme ultraviolet (EUV) case, highlighting the possible influence of an intermediate state on the photoionization process. We found no differences in the mass spectra when ionizing oxybenzone by single-photons between 17.2 and 35.7 eV. However, for the multiphoton ionization, the fragmentation process was found to be sensitive to the photoionization order and laser intensity. The "softest" method was found to be two-photon ionization using 4.7 eV light, which led to no measurable fragmentation up to an intensity of 5 × 1012 W cm-2.

Dynamic Effects on the Ionization-Induced Reactions of Methyl Halides: Quantum Mechanical and Molecular Dynamics Studies.

The mechanisms of the ionization-induced fragmentation and H migration of methyl halides CH3X (X = F, Cl, Br) have been examined by quantum mechanical and molecular dynamics methods. When CH3X (X = F, Cl, Br) is vertically ionized into a divalent cation, it can obtain enough excess energy to overcome the energy barrier of subsequent reaction channels for the formation of H+, H2+, and H3+ species and intramolecular H migration. The product distributions of these species greatly depend on the halogen atoms. The H+ formation decreases in the order of F > Cl > Br, which is inversely proportional to the increase in the magnitude of the energy barrier in the order of Br > Cl > F. This is attributable to the change in the charge distribution of the entire molecule by the halogen atoms. Meanwhile, the small H migration ratio for Cl and Br, despite their low energy barriers, was explained by the small sum of states at the transition state based on the Rice-Ramsperger-Kassel-Marcus (RRKM) theory. The H3+ formation ratio is unexpectedly smaller despite its low energy barrier. This is attributed to the dynamic effects of the H2 roaming that always occur prior to the reaction in question. Molecular dynamics simulations showed that the H2 roaming was restricted in a certain area due to an initially produced driving force on the hydrogen atoms in a certain direction by vertical ionization; this phenomenon suppresses the formation of H3+, which requires the hydrogen atoms to be in motion over a relatively wide range to enter the transition state region. Thus, the low proportion of the observed H3+ can be explained by the dynamical probability of the transition state structure formation.

Designing neodymium-doped hexamine complexant as novel IR NLO material with extremely large non-linear optical behavior.

A new complex named HMNd has been basically designed by doping rare-earth neodymium metal inside the hexamine surface HM. Density functional theory (DFT) calculations were carried out using B3LYP functional with split basis set GENECP to examine their geometrical, electronic, and non-linear optical properties of newly designed complex HMNd. After getting stable geometry of HMNd, its optoelectronic properties were compared with pure HM surface to check the influence of doping. HMNd revealed the obvious reduction in band gap energies from 8.4eV (HM) to 1.79eV (HMNd) as confirmed through DOS analysis. The highest hyperpolarizability and linear isotropic polarizability values of 6.8 × 105 a.u and 262.81 a.u respectively are perceived in HMNd. Electronic and thermodynamic stability of the designed complex has been confirmed through their vertical ionization and interaction energies. As revealed through the UV-visible analysis, doping with neodymium metal (HMNd) shifts the absorption to IR region with λmax of 2699.63nm which leads towards the production of new materials. These upshots highlight the adequacy of designed complex providing gateway for designing new IR NLO materials in laser frequency conversion technology having usages in versatile fields.

Attochemistry of hydrogen bonded amide and thioamide model complexes in protein following vertical ionization

Hydrogen bond in protein structure is a dynamic topic in research community. 2-Pyridone attached to amide forms hydrogen bond in the protein structure. Instead of amide, a number of model complexes such as thioamide in protein structure are used in recent research. Thioamide behaves potential surrogate of amide. To develop better understanding on the effect of ionizing radiation in protein, charge migration should be studied rigorously for the hydrogen bonded complexes such as amide:2-pyridone or thioamide:2-pyridone complexes. Hydrogen bond energies of these complexes are investigated in this context. Surprisingly, thioamide hydrogen bonded complexes are stronger in nature compare to amide hydrogen bonded complexes. This investigation centered on charge migration through amide and thioamide hydrogen bonded complexes and focused on different aspects of attosecond charge migration through these bonds. It is observed that charge migration occurs in amide hydrogen bonded complexes in 600–800 attoseconds time scale whereas it ceases for thioamide hydrogen bonded complexes.

Comprehensive Quantum Chemical Characterization of the Astrochemically Relevant HCnH Chain Family: An Attempt to Aid Astronomical Observations

AbstractIn this paper, the results of a comprehensive theoretical investigation of neutral HCnH0 and charged HCnH± chains are reported using state‐of‐the‐art compound model chemistries (W1BD, G4, CBS‐QB3, CBS‐APNO, CBS‐4M) and single point methods (including “gold standard” CCSD(T)). The properties envisaged include electronic and chemical bonding structure data, enthalpies of formation, adiabatic and vertical ionization (IP), and electron attachment (EA) energies, gas phase acidities, C−H bond strengths, and chain “deprotecting” (HCnH → H + Cn + H) energies. The best theoretical estimates based on composite models reported here for the various properties investigated agree with the available experimental data and are better than all previous theoretical estimates. To exemplify, for the enthalpies of formation, the G4 composite model achieves a RSMD (root square mean deviation) of 0.28 kcal mol−1 and a MUD (maximum unsigned deviation) of 0.45 kcal mol−1. Most importantly from the astrochemical perspective, it is predicted that the stable HCnH− anions with are nonlinear. Having sufficiently large dipole moments, the anion HCnH− cis conformers are potential candidates for detection in space via rovibrational spectroscopy.

Opening of the Diamondoid Cage upon Ionization Probed by Infrared Spectra of the Amantadine Cation Solvated by Ar, N2 , and H2 O.

Radical cations of diamondoids, a fundamental class of very stable cyclic hydrocarbon molecules, play an important role in their functionalization reactions and the chemistry of the interstellar medium. Herein, we characterize the structure, energy, and intermolecular interaction of clusters of the amantadine radical cation (Ama+, 1‐aminoadamantane) with solvent molecules of different interaction strength by infrared photodissociation (IRPD) spectroscopy of mass‐selected Ama+L n clusters, with L=Ar (n≤3) and L=N2 and H2O (n=1), and dispersion‐corrected density functional theory calculations (B3LYP−D3/cc‐pVTZ). Three isomers of Ama+ generated by electron ionization are identified by the vibrational properties of their rather different NH2 groups. The ligands bind preferentially to the acidic NH2 protons, and the strength of the NH…L ionic H‐bonds are probed by the solvation‐induced red‐shifts in the NH stretch modes. The three Ama+ isomers include the most abundant canonical cage isomer (I) produced by vertical ionization, which is separated by appreciable barriers from two bicyclic distonic iminium ions obtained from cage‐opening (primary radical II) and subsequent 1,2 H‐shift (tertiary radical III), the latter of which is the global minimum on the Ama+ potential energy surface. The effect of solvation on the energetics of the potential energy profile revealed by the calculations is consistent with the observed relative abundance of the three isomers. Comparison to the adamantane cation indicates that substitution of H by the electron‐donating NH2 group substantially lowers the barriers for the isomerization reaction.

КВАНТОВО-ХИМИЧЕСКОЕ МОДЕЛИРОВАНИЕ ЭФФЕКТИВНОСТИ ИСПОЛЬЗОВАНИЯ ПОЛИАРИЛЕНОВ В ИНТЕРФЕЙСНЫХ СТРУКТУРАХ

This paper gives quantum-chemical analysis of polyarylene efficient use in interface structures. Quantumchemical calculations were performed for molecular systems representing simulated polyarylene polymer systems. The research involved 18 representatives of this class of compounds. Quantum-chemical calculations were conducted for all molecules using B3LYP/6-31+G(d) density functional theory method, and such energetic parameters were theoretically assessed as total energies of molecules and their negative and positive ions in molecular and optimized ionic geometries, energies of occupied and vacant molecular orbitals, magnitudes of vertical and adiabatic electron affinity and ionization potential as well as the dipole moment. The paper puts forward an algorithm for processing the results of quantum-chemical calculations based on the analysis of energy characteristics for monomeric units of polymers that makes it possible to reveal a certain relationship between chemical structure of an organic compound and electronic properties of the polymer-metal interface. The proposed algorithm allowed finding maximum deflection zones of energetic parameters and specific compounds, which are of interest for the formation of heterostructures.

Charge transfer and hydrogen adsorption in the Pd/Ag bimetallic nano system: an experimental and theoretical DFT cluster approach

We aimed to understand the characteristics of bimetallic systems samples with porous and large surface areas. In doing this we studied in particular the surface structure of the Pd/Ag system. Our cluster models were based on high resolution transmission electron microphotographs of samples with defects. For the modelling of our Pd/Ag nano systems, we combined a variety of experimental and theoretical methods, such as: sputtering, acrylamide sol–gel, high resolution transmission electron microscopy, energy dispersive X-ray spectrometry, and density functional theory. This study explores the connection between nanocrystal structure, electron density distribution, and charge transfer. Charge transfer was determined via density difference analysis. Charge density as a function of the orbital radius was calculated. Vertical electron affinity, vertical first ionization potential, and vertical electronegativity of the Pd 18 and Ag 24 clusters were calculated. In addition, Voronoi, Bader, Becke, Loewdin, Mulliken, NPA, and NBO population analyses were conducted.

Structural and electronic properties of Gen and EuGen-1 nanoclusters: A full potential DFT study

In this work, the stability, structure and electronic properties of the nanoclusters of germanium (Gen) and europium atom doped germanium clusters (EuGen-1) with n=2 to 12, 15 and 20 were investigated. First, the stability of nanoclusters such as Gen and EuGen-1 was addressed using FHI-aims as a software package based on the density functional theory. Then the lowest-energy structures were selected for calculating the first vertical ionization with the symmetry adapted cluster-configuration interaction General-R (SAC-CI-General-R) method. The results of this research show that there is a good agreement between calculation and experiment ionization potential for Gen nanoclusters. Generally, the analyses of binding energies show that increasing the size of nanoclusters leads to more stability for nanoclusters. The most stable nanoclusters for EuGen can be created with exchanging the Eu atom in the most stable Gen+1 nanoclusters, but there is an exception for n=11 case. Here, the second difference in energy (∆2E) and gap energy are computed for the stable nanoclusters. The results of ionization energy and second difference in energy confirm that Ge7 and Ge10 also EuGe8 and EuGe10 have the most stability.

Double and Triple Ionisation of Isocyanic Acid

Double and triple ionisation spectra of the reactive molecule isocyanic acid (HNCO) have been measured using multi-electron and ion coincidence techniques combined with synchrotron radiation and compared with high-level theoretical calculations. Vertical double ionisation at an energy of 32.8 ± 0.3 eV forms the 3A” ground state in which the HNCO2+ ion is long lived. The vertical triple ionisation energy is determined as 65 ± 1 eV. The core-valence double ionisation spectra resemble the valence photoelectron spectrum in form, and their main features can be understood on the basis of a simple and rather widely applicable Coulomb model based on the characteristics of the molecular orbitals from which electrons are removed. Characteristics of the most important dissociation channels are examined and discussed.

Substitution Effects on the Optoelectronic Properties of Coumarin Derivatives

Coumarin derivatives have gathered major attention largely due to their versatile utility in a wide range of applications. In this framework, we report a comparative computational investigation on the optoelectronic properties of 3-phenylcoumarin and 3-heteroarylcoumarin derivatives established as enzyme inhibitors. Specifically, we concentrate on the variation in the optoelectronic characteristics for the hydroxyl group substitutions within the coumarin moiety. In order to realize our aims, all-electron density functional theory and time dependent density functional theory calculations were performed with a localized Gaussian basis-set matched with a hybrid exchange–correlation functionals. Molecular properties such as highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies, vertical ionization (IEV) and electron affinity energies, absorption spectra, quasi-particle gap, and exciton binding energy values are examined. Furthermore, the influence of solvent on the optical properties of the molecules is considered. We found a good agreement between the experimental (8.72 eV) and calculated (8.71 eV) IEV energy values for coumarin. The computed exciton binding energy of the investigated molecules indicated their potential optoelectronics application.

Extremely large nonlinear optical response and excellent electronic stability of true alkaline earthides based on hexaammine complexant

Geometric, electronic and nonlinear optical properties of a new class of excess electron compounds (alkaline earthides) have been investigated. The rational design principle involves judiciously placing alkali metals inside the hexaammine complexant to serve as excess electron source for alkaline earth metals placed outside the complexant. By utilizing hexaammine as the complexant, nine different compounds M+(Hexaammine)M− (M = Li, Na and K; M− = Be, Mg and Ca) are studied. The alkaline earthides are quite stable electronically and thermodynamically, as revealed from their vertical ionization and interaction energies, respectively. The true alkaline earthide characteristic is confirmed through NBO charges and frontier molecular orbital analysis. The alkaline earthides show remarkable nonlinear optical responses with the first hyperpolarizabilities (βo) up to 6.4 × 105 au. The higher hyperpolarizabilities values are attributed to the presence of excess electron on alkaline earth metals in polarized p-orbitals which is confirmed through the partial density of states (PDOS) spectral analysis. The hyperpolarizabilities are rationalized through two level method analysis. The projection of hyperpolarizability on the dipole moment is analyzed through βvec calculations. Quite contrary to other excess electron materials, the alkaline earthides show excellent nonlinear optical response despite moderate to high crucial excitation energies. These alkaline earthides will pave the path for further exploration of electronically stable high performance NLO materials.

Ultrafast Charge Transfer and Structural Dynamics Following Outer-Valence Ionization of a Halogen-Bonded Dimer.

We study the temporal evolution of the CH2O···ClF halogen-bonded dimer following vertical ionization out of outer-valence molecular orbitals on a femtosecond time scale, employing mixed quantum-classical molecular dynamics simulations. The charge density pattern in the ground state that is suitable for the formation of the ground-state halogen bond can be changed upon ionization. Depending on the molecular orbital that gets ionized, the change in the charge density transiently strengthens or weakens the halogen bond through altering the electrostatic interaction. A transient increase in the halogen bond strength is observed if the ionization enhances the positive charge on the halogen atom provided that the electron donor site possesses some negative charge. The evolution of the system following ionization is driven by energetic stabilization through transferring the electronic charge from the halogen bond acceptor/electron donor (CH2O) to the halogen bond donor/electron acceptor (ClF). The charge transfer oscillations are at the same time governed by the covalent bond vibrations.

IcMRCI+Q study on spectroscopic properties and predissociation mechanisms of electronic states of BF+ cation

In this paper, we study the spectroscopic properties and predissociation mechanisms of 14 states, which come from the first two dissociation channels of the BF+ cation. The potential energy curves of 14 Λ-S (X2Σ+, 12Π, 22Π, 22Σ+, 14Σ+, 14Δ, 14Σ1, 12Δ, 12Σ1, 32Σ+, 14Π, 24Π, 24Σ+, and 32Π) and corresponding 30 Ω states are calculated using the complete active space self-consistent field method, which is followed by the valence internally contracted multireference configuration interaction approach with the Davidson modification. To improve the reliability and accuracy of the potential energy curves, the core-valence correlation and scalar relativistic corrections, as well as the extrapolation of potential energy to the complete basis set limit are taken into account. The spin-orbit coupling is computed using the state interaction approach with the Breit-Pauli Hamiltonian. Based on these potential energy curves, the spectroscopic parameters and vibrational levels are determined for all the bound and quasi-bound Λ-S and Ω states. The present ground-state spectroscopic constants match well with the available experimental data. In addition, the vertical and adiabatic ionization potentials from the X1Σ+ state of BF molecule to the X2Σ+, 12Π, and 22Σ+ states of BF+ cation are calculated. The results of BF+(X2Σ+) ← BF(X1Σ+) ionization are in good agreement with the measurements. Various curve crossings of Λ-S states are revealed. We calculate the spin-orbit matrix elements between two interacting electronic states in the curve crossing region. With the help of present spin-orbit coupling matrix elements, we analyze the predissociation mechanisms of X2Σ+ and 32Π states along with the perturbations of the nearby states to 22Π, 14Σ+ and 32Σ+ states for the first time. The predissociation of X2Σ+ and 32Π states have a chance to occur around the vibrational levels υ"=30 and υ'=0 due to spin-orbit coupling, respectively. The present results also indicate that the υ' ≥ 9 vibrational levels of 22Π state are perturbed by the crossing states 22Σ+, 14Σ+, 14Δ, 14Σ1, 12Δ, 12Σ1, 32Σ+, and 14Π, that the υ' ≥ 4 vibrational levels of 14Σ+ state are perturbed via the interacting states 14Σ1 and 12Σ1, and the great perturbations between υ' ≥ 4 vibrational levels of 32Σ+ state and υ' ≥ 0 vibrational levels of 14Π state. For the 30 Ω state, we also calculate the relative energies of dissociation limits compared with the lowest one matching well with the experimental ones. Finally, the Franck-Condon factors, Einstein coefficients, and radiative lifetimes are evaluated for the 22Π (υ'=0-9)-X2Σ+, 22Σ+ (υ'=0-2)-X2Σ+, (3)1/2-(1)1/21st well, and (2)3/2 (υ'=0-9)-(1)1/21st well transitions.

On lithium doping in two stable nano-flakes of the B24: The double-ring versus the quasiplanar configuration

The stable local minima due to the addition of the Li atom to the double-ring and the quasiplanar configurations of the B24 molecule have been searched on the doublet potential energy surface to reveal the structural and electronic features of the Li@B24 system. We report two and seven stable local minima without imaginary vibrational frequency for the Li@B24(double-ring) and the Li@B24(quasiplanar) systems, respectively. The criteria of the adsorption energy, the vertical ionization (VI) energy, the deformation energy, the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energy gap, the atomic charges, the spin density distribution, the electron transfer (ET), atoms in molecules (AIM) analysis and the nonlinear optical (NLO) properties have been investigated for all the reported molecules of the Li@B24 system in the present paper. Our results present that both thermodynamic and chemical stability of the Li atom doping to the quasiplanar configuration of the B24 molecule are more than those of the double-ring configuration. Additionally, both the double-ring and the quasiplanar configurations can produce the Li@B24 system with values of high first hyperpolarizability (βtotal) due to the Li atom doping. In all the reported molecules of the Li@B24 system, electron density of the Li atom decreases due to the existence of the double-ring and the quasiplanar configurations confirming the role of the electron donor for the Li atom. In contrast, both decreasing and increasing electron density have been observed in the B atoms of the Li@B24 system. However, the role of electron acceptor (increasing electron density) for the B atoms is more dominant than the role of electron donor (decreasing electron density). This result highlights chemical flexibility of the B atoms.

Attochemistry of Ionized Halogen, Chalcogen, Pnicogen, and Tetrel Noncovalent Bonded Clusters.

In general, charge migration can occur via pure electron-electron correlation and relaxation or via coupling with nuclear motion. We must understand both aspects of charge migration through the non-hydrogen noncovalent bonds to harness full potential of the halogen-, chalcogen-, pnicogen- and tetrel-bonded photosensitive functional materials. This feature article, however, is focused on the pure relaxation- and correlation-driven charge migration, subsequent charge localization, and finally on charge-directed reactivity in the non-hydrogen noncovalent bonded clusters. Pure relaxation- and correlation-driven charge migration can occur on a several hundred attosecond (as) time scale, and this is why chemical dynamics associated with this pure electronic charge migration can be named "attochemistry". One of the efficient ways to elucidate the attochemistry is via the vertical ionization by monitoring a nonstationary electronic charge density that evolves in time while the nuclear configuration remains unchanged. So far, attochemistry of several halogen-, chalcogen-, pnicogen-, and tetrel-bonded clusters has been studied theoretically by our group. All the interesting predictions have been summarized in this Feature Article. The time scales of relaxation- and correlation-driven charge migration through the halogen, chalcogen, pnicogen, and tetrel noncovalent bonds are found to be quite similar (approximately in the range of 300-600 as) in different (1:1) AX:NH3 and AX:OH2 complexes (where A represents different substituents, such as NH2, CN, etc.). Basis sets do not exhibit any effect on the predicted charge migration time scale. A very long intermolecular distance (approximately more than 10 Å), for which (physically) no noncovalent bonding interaction can be present, ceases the intermolecular charge migration. The strength of the electron-electron correlation interaction influences the charge migration through these noncovalent bonds, making charge migration faster with a higher correlation interaction. The initial nuclear configuration affects the charge migration through the non-hydrogen noncovalent bonds. For large clusters, in which both hydrogen and non-hydrogen noncovalent bonds are formed, non-hydrogen noncovalent bonds are found to facilitate the charge migration preferentially over the hydrogen bonds. As a result of nuclear wavepacket delocalization, the attosecond charge oscillation in noncovalent bonded clusters decoheres. This renders charge localization. Subsequent charge-directed reactivity is discussed. This article is the first review on the attochemistry of non-hydrogen noncovalent bonded clusters.

On the Attosecond charge migration in Cl…..N, Cl…..O, Br…..N and Br…..O Halogen-bonded clusters: Effect of donor, acceptor, vibration, rotation, and electron correlation

The electron-electron relaxation and correlation-driven charge migration process, which features pure electronic aspect of ultrafast charge migration phenomenon, occurs on a very short timescale in ionized molecules and molecular clusters, prior to the onset of nuclear motion. In this article, we have presented nature of ultrafast pure electronic charge migration dynamics through Cl…..N, Cl…..O, Br…..N, and Br…..O halogen bonds, explored using density functional theory. We have explored the role of donor, acceptor, electron correlation, vibration and rotation in charge migration dynamics through these halogen bonds. For this work, we have selected ClF, Cl2, ClOH, ClCN, BrF, BrCl, BrOH, and BrCN molecules paired with either NH3 or H2O. We have found that the timescale for pure electron-electron relaxation and correlation-driven charge migration through the Cl…..N, Br…..N, Cl…..O, and Br…..O halogen bonds falls in the range of 300–600 attosecond. The primary driving force behind the attosecond charge migration through the Cl…..N, Br…..N, Cl…..O, and Br…..O halogen bonds is the energy difference (ΔE) between two stationary cationic orbitals (LUMO- β and HOMO- β), which together represents the initial hole density immediately following vertical ionization. We have also predicted that the strength of electron correlation has significant effect on the charge migration timescale in Cl…..N, Br…..N, Cl…..O, and Br…..O halogen bonded clusters. Vibration and rotation are also found to exhibit profound effect on attosecond charge migration dynamics through halogen bonds. The attosecond charge migration dynamics through Cl…..N, Cl…..O, Br…..N, and Br…..O halogen bonds depends on strength of electron correlation, donor and acceptor, the energy difference (ΔE) between two stationary cationic orbitals (LUMO-β and HOMO-β) involved in electronic superposition, vibration and rotation.

On the ultrafast charge migration dynamics in isolated ionized halogen, chalcogen, pnicogen, and tetrel bonded clusters

Here we demonstrate, compare and contrast relaxation- and correlation-driven charge migration dynamics in halogen, chalcogen, pnicogen and tetrel bonded clusters, following their vertical ionization. For this work, we have selected different isolated A–X:NH3 clusters, where A represents F, Cl, CN and NH2 substituents and X features Cl, SH, PH2 and SiH3 to exhibit specific noncovalent bonding interaction. The charge migration dynamics in these clusters is studied using the density functional theory (DFT) with the wB97XD functional and the 6-31+G(d,p) basis set. Approximately 400–600 attosecond time scale is predicted for charge migration in (1:1) AX:NH3 complexes. Effects of basis set and intermolecular distance on the ultrafast charge migration dynamics through the halogen, chalcogen, pnicogen, and tetrel bonded clusters are also discussed. This is the first report on pure relaxation- and correlation-driven charge migration dynamics in chalcogen, pnicogen and tetrel bonded clusters.

Ethynyl substitution effect on the electronic excitation spectra of aniline

We made an extended study on the structure and properties of the low-lying electronic states of ethynyl substituted aniline and their cations. We performed these calculations using density functional theory method(B3LYP and CAM-B3LYP DFT) and the complete active space self-consistent field(CASSCF) approach in connection with the aug-cc-pVZ Dunning’s basis sets and concerted ANO-L-VDZP basis sets. Our results included their equilibrium geometries, the vertical excitation spectra and the vertical and adiabatic ionization energies. The effect of ethynyl substitution on the electronic structure and the spectroscopy of aniline was probed.