Electronic Charge Density Distribution Research Articles

Exploration of one-dimensional hydrogen bonding organic framework (1D-HOF) and charge transfer dynamics in N’-benzylbenzohydrazide: A comprehensive structural and quantum computational investigation

This study presents a comprehensive structural analysis of N’-benzylbenzohydrazide (NBBH) using experimental and computational techniques, shedding light on its non-covalent interactions and charge transfer dynamics. Single crystal X-ray diffraction studies confirm the three-dimensional molecular structure with high precision, revealing an orthorhombic crystal system and non-planarity of the NBBH molecule. Supramolecular interactions, including hydrogen bonds and short intermolecular interactions, are investigated, forming the basis for the assembly of molecular entities into extensive frameworks. Hirshfeld surface analysis provides insights into the intermolecular interactions in the crystal system, with the visualization of hydrogen bonds and short contacts. Energy framework analysis further explores pairwise interaction energies, emphasizing the role of dispersive forces in stabilizing the crystal lattice. Density functional theory studies, including molecular orbital analysis and global chemical reactivity descriptors, offer a deeper understanding of the electronic structure, redox potential, and charge transfer properties of NBBH. Natural bond orbital analysis reveals the charge transfer mechanism within the 1D Hydrogen-Bonded Organic chain, highlighting hyperconjugative interactions contributing to the stabilization of the molecule. Non-covalent interaction analysis using the Reduced Density Gradient method visualizes intra and intermolecular interactions, providing valuable insights into the formation and stability of the 1D network chain in the crystal structure of NBBH. Reorganization energy is discussed in the context of electron and hole transfer processes, emphasizing its importance in understanding the charge transfer dynamics within the molecular framework. The observed inverse relationship between reorganization energy and charge mobility contributes a key insight into the stability and conductivity of the material. The electron charge density distribution analysis, provides a detailed spatial distribution of electrons within the NBBH molecule. The findings have implications for understanding the molecular properties and potential applications of NBBH in various fields.

Nanocluster-mediated electron–hole separation for efficient CO2 photoreduction

Poor capability of charge-holes separation and slower surface CO2 reaction kinetics hinder photocatalytic performance. Here, SnS2 atomic layer with Pt3Co alloy nanoclusters have been successfully prepared. Nanoclusters could be used as highly catalytic active sites, which not only facilitates the carrier separation and transport kinetics, but enriches electrons lowered the reaction barrier. As expected, the CO evolution rate of the champion SnS2/Pt3Co catalyst was 13.6 times higher than that of the original SnS2 catalyst under white light irradiation. In-situ DRIFTS identifies key intermediate in the photoreduction process. In-situ XPS and DFT calculation further verifies the electron transport direction and charge density distribution at the SnS2/Pt3Co interface. Our work uncovers the role of nanoclusters in carrier separation and transport as well as proton transport, opening new chances for obtaining efficient photoreduction CO2 property.

Electronic and optical characteristics of long-period stacking ordered phases in Mg-Y-Zn alloys: A first-principles study

Electronic and optical properties of long-period stacking order (LPSO) phase in Mg-Y-Zn alloy are calculated and analyzed by first principles in this paper. The electronic properties and thermodynamic stability of 14 H and 18 R LPSO phases were studied by means of electron density of state (DOS), COHP analysis, electron localization function (ELF) and charge density distribution, and their optical properties, including absorption coefficient, reflectivity, refractive index, energy loss function and extinction coefficient, were discussed, and their variation trends with photon energy and related factors were analyzed. The findings indicate that both phases possess metallic characteristics and exhibit no energy gap. Furthermore, the thermodynamic stability of the 14 H phase surpasses that of the 18 R phase, owing to its stronger covalent bonds metal mixed bonds. In terms of absorption coefficients, both phases display high values within the energy range of 0–19 eV, with their most potent absorption peaks occurring at photon energies of 4.48 eV and 4.8 eV for the 14 H and 18 R phases, respectively. Moreover, the photon absorption rate is inversely proportional to the density of L12 clusters in both phases.

The new solid solution of double transition metal MXenes: Atomistic modeling of two-dimensional YScX (X= C and N)

In this paper, the structural and dynamical stability, electronic, optical, and thermodynamic properties of a new solid solution of two transition metals YScX (X = C and N) MXenes have been studied. The calculation is carried out based on density functional theory (DFT) and the pseudopotential technique. The results obtained from the structural, thermodynamical, and dynamical stability have shown that 2D YScC and YScN MXenes are structurally stable and their experimental synthesis is possible. Total density of states and band structure calculations show that YScX (X = C and N) MXene exhibits metallic behavior using LDA, GGA, and GGA + HSE06 approximations. According to the total density of states results, it can be concluded that the YScX MXenes have a pseudogap close to the Fermi level and at the left side, which justifies the structural stability of the studied monolayers. The plots of electron charge density distribution and electron localization function justify the metallic nature of the mentioned structures. The large negative values of the real part of the dielectric function indicate that 2D YScX (X = C and N) MXenes have a metallic Drude-like behavior. The saturation of the surface of 2D monolayers with various F, O, OH, and H functional groups does not change the metallic properties, the only exception that reveals the semiconductor property in the HSE06 method is YScCH2 Mxene where no atomic orbital intersects the Fermi level. In addition, the onset of the absorption spectrum of YScX (X = C and N) MXenes corresponds to zero photon energy, which is a confirmation of the metallic properties of the investigated structures. The GGA + HSE06 method enables faster electromagnetic beam propagation through the 2D materials, particularly in the x-direction of the hexagonal structure, resulting in a lower absorption coefficient and optical conductivity of 2D monolayers compared to the GGA method. The rising trend of entropy with temperature provides evidence for the endothermic behavior of YScC and YScN monolayers. Unlike heat capacity, the Debye temperature of YScX (X = C and N) MXenes decreases with respect to temperature T, according to the inverse relationship between the Debye temperature and the heat capacity. Due to structural and dynamic stability and layered structure with the nature of covalent and metallic bonds, YScX MXenes are a suitable choice for use in electrical connections and as a protective coating with a low friction level.

Computational Study for Insight into LixNiO2 Interlayer Collapse and Pillar Dopant to Counter Oxygen Charge-Transfer at High Depth of Charge (x < 0.25)

As demand for high power and energy capacity has continued to rise, increasing nickel content in Li[Ni1-y-zCoyMnz]O2 (NCM) or Li[Ni1-y-zCoyAlz]O2 (NCA) cathode materials has been the subject of extensive study to improve the specific capacity of Li-ion batteries. Commercialized (Ni composition ~60%) NCM/NCA can deliver specific capacity near 170 mAh/g while LixNiO2 (LNO) has been shown to offer over 200 mAh/g, but coincidently suffers from instability, and anisotropic volume strain due to Ni(III)-O6 Jahn-Teller (JT) distorted shearing and especially lattice collapse during charging. The resulting crack formation in primary particles and pulverization of secondary particles increases surface area exposed to the liquid electrolyte and accelerates phase decomposition due to oxygen evolution and side reactions, with capacity fading increasingly well studied and characterized, including the known chemical instability of Ni—O system yields oxygen redox and evolution at LNO surfaces near 4.2 V. In potential solid-state battery applications, the mechanical nature of large anisotropic strain will incur broken contact with solid electrolyte and shorten lifespan. As the most critical lattice collapse occurs in charging beyond 75% de-lithiation (x < 0.25), mitigation by implementing cutoff voltage near 4.2 V (vs Li anode) has commonly been implemented, consequently restricting practical energy density. Detailed analysis of electronic charge and charge density distribution via first-principles calculations reveals oxygen-nickel charge transfer during charge/discharge is well correlated to oxygen-cation coordination. While charging, each Ni layer shrinks monotonically throughout de-lithiation, from 2.17 Å to 1.9 Å, and the Li interslab thickness first increases, from 2.55 Å to 2.82 Å at 75% de-lithiation, then decreases to 2.48 Å. The former is consistent with the perspective of Ni(III) [3d7: t2g 6 eg 1] oxidation to smaller Ni(IV) [3d6: t2g 6 eg 0], collaborated by respective magnetic moments, a / b lattice constant decrease, and Ni-O bond length changes associated with the loss of JT distortion. The interslab behavior, however, requires recognition of Ni-O bonding character of eg states, where modeling the interslab expansion and collapse in finer detail confirms approximately linear behavior in each regime, notably collapsing even with low but finite Li (e.g. 20-8%) in each interlayer (no empty layers or stacking order transitions). By Bader charge analysis, it is found that Ni exhibits less redox activity directly; rather oxygen charge is more significantly depleted due to charge transfer as eg bonding states are de-occupied by electrons during charge, indicated in projected density of states. Smaller and substantially charge-depleted oxygens appear around 25% Li content and were all identified as oxygens lacking any Li nearest neighbors. Intuitively, as concentrations progress below 25% (> 4.2 V), the number of such oxygen rapidly increases with a corresponding dwindling of higher charge state oxygens local to the few remaining Li. The interslab (Li-layer) thickness decrease follows from these smaller oxygen ins and significantly lessened repulsion across the Li layer in local close-packed, O3 stacking sequence. To mitigate the collapse, high valent cations as dopants at Li-site are investigated in similar detail with this mechanism in mind. Potential cations were chosen on a basis of compatibility with Li-site octahedra, with radii similar to Li+, and less comparable to Ni(II), Ni(III), or Ni(IV). Models of LNO doped as Lix-yMyNiO2 are found to donate charge to all six neighboring oxygen and the respective NiO6 octahedra throughout de-lithiation (decreasing x, 1 > x > y). The charge-compensated oxygens retain stronger local coulomb interaction near the cation dopant and provide a pillaring effect to reduce lattice collapse even to 100% depth of discharge. Select dopants indicate low anisotropy and volumetric strain, e.g. ∆V/V ~ 2% over the range of 0-90% capacity. The presented role of cation dopants reinforces the promise of “zero-strain” LNO cathode material, with simultaneous improvement to thermal and mechanical stability, encouragingly reported by experimental works, and both greater capacity and power by unlocking deeper charging.

Cg…Cg interactions driven 1D polymeric chains bridged by lattice solvents in N3-(2-pyridoyl)-4-pyridinecarboxamidrazone Pb(II) complex

This study will shed light on the non-covalent interactions present in the N3-(2-pyridoyl)-4-pyridinecarboxamidrazone Pb(II) complex [(L)Pb(CH3OH)(H2O)2] and their significance in the context of crystal packing and material properties. The complex was synthesized and characterized using single crystal X-ray structural analysis, providing valuable insights into its molecular structure. Our focus was on analyzing the non-covalent interactions in the crystal structure, where these interactions played a crucial role in the formation of one-dimensional network chains observed in the crystal. To quantitatively analyze these interactions, we employed Hirshfeld surfaces analysis. Furthermore, we performed density functional theory computational studies to calculate the molecular geometry and global reactive parameters, allowing us to gain a better understanding of the properties of the novel molecule. The molecular electrostatic potential was plotted to visualize the charge distribution and identify the electrophilic and nucleophilic sites in the molecule. Finally, we explored the non-covalent interactions and electron charge density distribution using the QTAM and NCI models, providing further insights into the complex's behavior. This study contributes to the understanding of non-covalent interactions in the context of crystal growth and design, and expands the knowledge of the structural and electronic properties of the N3-(2-pyridoyl)-4-pyridinecarboxamidrazone Pb(II) complex.

Crystal structure and physical properties of Ti2B5 predicted by first principles calculations

Applying the advanced CALYPSO structure searching method and first principles calculations, we predict a novel superhard structure for Ti2B5, which belongs to the monoclinic C2/m space group. The previously known Hf2B5, W2B5, and δ-V2O5-type structures are also selected as the potential structures for Ti2B5. It is shown that the predicted C2/m structure is the most stable phase among these considered structures within the range of 0-100GPa. The calculations of the phonon dispersion and elastic constants affirm that the predicted C2/m phase is dynamically and mechanically stable. The predicted high shear modulus (249 GPa) and large hardness (46.9 GPa) show that it should be anunderlying superhard material. In addition, the elastic anisotropy of Ti2B5 is also explored by investigating the directional dependence of the Young's modulus, shear modulus, and Poisson's ratio as well as some well anisotropy indices. The particular analyses of the density of states and electron charge density distribution verify that the strong B-B and Ti-B covalent bonds in the predicted C2/m-Ti2B5 phase playan importantpartin its hardness and structural stability.

Influence of hydroxyl group in stabilizing the Schiff base crystal structure: Crystal structure, computational and molecular docking studies

To investigate the synergetic effect in the formation of crystal structure having two independent molecules in the asymmetric unit and the structure-property relationship of the molecule, we have synthesized the Schiff base compound (E)-4-(((4-chlorobenzyl)imino)methyl)benzene-1,2,3-triol. The formation of the desired compound was confirmed by the FTIR and single-crystal X-ray studies. The enriched hydroxyl group exhibits more intra and inter-strong hydrogen bonds. The chlorine-hydrogen and C6-H6‧‧‧π interaction along with other interactions form a supramolecular architecture. The Hirshfeld surface analysis and 2D fingerprint analysis provide valuable information about the intermolecular interaction present in the crystal structure. The likelihood of occurrence of intermolecular contacts present in the crystal structure was analyzed using enrichment ratio. The visualization of the interaction topology along with interaction energy between the molecules are carried out using an energy framework. QTAIM, NCI, ELF and LOL studies provide information about electron charge density distribution and the nature of intramolecular and dimeric interaction. The DFT studies provide ground state energy of the optimized structure and the HOMO-LUMO energy gap. The molecular electrostatic potential provides the reactive site and anisotropy of charge distribution of chlorine atom. The NBO studies provide stabilization energy associated with the delocalization of orbitals. The docking studies were also carried out for SARS COVID-19 and the effect of hydroxyl group substitution on binding interaction was investigated.

Material Selection Analysis of New Partial Discharge Sensor Electrode Plate Based on First-Principles Study.

Graphene is well known for its electrical properties and can be used for sensor improvement. The first-principles study is one of the powerful tools to analyze and predict the performance of advanced materials. In this paper, microscopic material selection is performed for partial discharge sensor electrode plate materials based on first-principles study. By introducing graphene, six different microscopic electrode plate models are built based on the traditional metal electrode plates. Electrical properties including electronic structure, charge density and charge distribution of electrode plates are analyzed from the microscopic perspective when the actual partial discharge electric field is 1 V/m. Additionally, electrical transport properties of electrode plates are determined by electrical transport calculation. The results show that the double-layer graphene copper-clad electrode plate has better electrical transport capacity and higher gain characteristics when used in partial discharge sensors. This study fills the gap in the microscopic electric transport response mechanism of electrode plates, which can provide theoretical support for the improved design of partial discharge sensors.

Exploration of the structural, vibrational, electronic, mechanical and thermal properties of Ru4Al3B2 and Ru9Al3B8: a DFT study.

The structural, dynamical, electro-optical, mechanical, and thermal characteristics of the newly synthesized intermetallic compounds Ru4Al3B2 and Ru9Al3B8 have been studied under ambient and elevated pressure through density functional theory (DFT). The obtained lattice parameters of the compounds are consistent with the experimental values. The metallic character of these compounds is established by the band structure and density of states (DOS). The electronic charge density distribution and bond analysis imply that Ru4Al3B2 and Ru9Al3B8 have mainly both ionic and covalent bonding. The non-negative phonon dispersion frequency of the compounds reaffirms their dynamical stability. Both compounds are tough as well as have high melting points, and hence, can be applied in harsh conditions. Mechanical properties are significantly improved under pressure. Thermal barrier coating (TBC) is a possible field of application for both compounds. The different thermal properties such as the Debye temperature (ΘD), Grüneisen parameter (γ), melting temperature (Tm), minimum thermal conductivity (Kmin) and lattice thermal conductivity (κph) of these compounds have been studied to figure out the suitable application areas in thermally demanding situations. The pressure and temperature dependent bulk modulus (B) and other thermodynamic properties have also been analyzed, which suggested that the present compounds are strong candidates for device applications at high temperature and pressure. Owing to their high optical absorptivity and reflectivity in the UV region, they are also candidates for UV-based applications. Furthermore, they also have applicability in the fields of electronics, aviation, energy storage, and supercapacitor devices for their superior electronic, thermal and mechanical properties.

Anion and radical anion products of flutamide studied by IR spectra and density functional calculations

Flutamide, antiandrogen drugs for prostate cancer, was studied by spectroscopic and DFT methods to estimate its ability to form anion and radical anion products. The azanion was generated in DMSO‑d6 solution by treatment with sodium methoxide and the resulting spectral changes were followed by IR spectroscopy. IR measurements in electrochemical solution cell were performed to characterize the reductive behavior of flutamide. The different conformers of flutamide, its anion and radical anions, the spectral changes expected related to the conversion into anionic species and several molecular parameters were computationally estimated based on DFT. The structure, electronic charge and spin density distribution of azanion and protonated/deprotonated radical anion species were assessed by correlating the observed IR changes to the predicted vibrational frequencies and based on calculated structural parameters. The obtained information may enhance the understanding of the possible routes for metabolizing and interaction of flutamide with biomolecules relevant to its therapeutic action.

Quantum Mechanical Calculations and Electrochemical Study of Vibrational Frequencies, Energies in Some Flavonoids molecules

Quantum mechanical computations is conducted using DFT (Density Functional Theory) and PM3 (Parameterized Model 3), also, using DFT of (B3LYP) with a 6-311++G (d, p) with G09 application. These molecular three components include structure, electronic charge density and energetic characteristics of chosen phytomedicine compounds. The impact of functional groups on physical characteristics were studied using myricetin, linebacker, and flavone because of their chemical structures. For phytomedicine compounds, we utilized quantum mechanical simulations to estimate bond length, energy, vibration(vib.) modes, charge density and mechanical properties (cruelty, strength, stiffness, for the measurements of the lengths and energy of the bonds). Herzberg convention is used to look for the connections between the frequencies of similar modes which was used. IR absorption of the highest vibration frequencies modes of 3N-6 was measured and assigned for all species. Physical parameters were also calculated these include: heat of production, amount of energy, atomic electronic charge density, dipole moment and (E gap) (E = ELUMO-EHOMO). For three phytomedicine molecules, quantum chemical properties were combined. This software also computed and evaluated the electronic charge density distribution on atoms of 3 molecules. The equilibrium geometries of all three molecules were studied.

Electronic band structure and chemical bonding in trigonal Se and Te

Herein, the electronic band structure and charge density distribution are theoretically studied in trigonal Se and Te to clarify the uncertainty stemming from the different views on the types of chemical bonding in their crystals and to reconsider the role of valence s- and p-electrons in bonding. The lack of overlapping of the lower and upper bands of valence p-electrons in trigonal Se and the large band separation of valence s- and p-electrons present an opportunity to estimate the contributions of valence s- and p-electrons to the charge densities of two types of bond critical points (BCPs) in trigonal Se. Valence s-electrons and lower p-electrons significantly contribute to the charge density of BCPs of the first type, covalently connecting the nearest neighboring atoms within helical chains. In contrast, the lower and upper valence p-electrons are mainly responsible for the BCPs of the second type linking the neighboring chains in the Se and Te trigonal crystal structures. The nonlocal long-range van der Waals (vdW) correlation functional vdW-DF2, which is important for determining lattice constants, has a minimal effect on BCP parameters, which define the chemical bonding types. The exchange potential of Becke and Johnson modified by Tran and Blaha and the short-range electron–electron correlations considered in the local density approximation correctly reproduce not only the energy bandgap values but also various peculiarities in the electronic band structure of trigonal Se and Te, such as band crossings (Weyl nodes) of the valence p-electrons recently found in trigonal Te via angle-resolved photoemission spectroscopy experiments.

Suppression of the superconducting phase in new structures of elemental sulfur at terapascal pressures

We perform a computational structure search and study the phase diagram of elemental sulfur up to 100 TPa from first-principles using ab initio random structure searching (airss), discovering six new phases with the transition sequence $\text{bcc}\ensuremath{\rightarrow}I{4}_{1}/acd\ensuremath{\rightarrow}cI16\ensuremath{\rightarrow}\ensuremath{\alpha}\text{-U}\ensuremath{\rightarrow}\text{hcp}\ensuremath{\rightarrow}A15\ensuremath{\rightarrow}\text{bcc}$. The electronic properties and charge density distributions of the new phases are extensively studied. Remarkably, upon transition to the $I{4}_{1}/acd$ phase at 1.24 TPa, the superconducting critical temperature of sulfur abruptly drops from 12 K to just 0.4 K, and above 5 TPa, we find the critical temperature to be zero up to at least 100 TPa. We show that this sudden suppression of superconductivity is coincident with the formation of a sequence of electride phases, which feature significantly reduced electron-phonon coupling and substantial charge localization. Despite ceasing to be a superconductor, sulfur remains metallic up to at least 100 TPa.

Compton profile and charge density reconstruction by the maximum entropy method

The aim of this work is to propose a theoretical procedure to determine the electron momentum density and Compton profile of valence electrons in solids. The procedure consists in a hybrid methodology that combines the maximum entropy method and Dirac-Hartree–Fock formalism, which allows including exchange and correlation effects on valence electrons for distances near the atomic nucleus and that are approximated using the Breit-Wigner distribution function. This technique can be applied for a wide range of crystalline solids. The results and comparisons reported here are for: lithium, beryllium, aluminum, silicon and copper. The application of the model only requires prior knowledge of the Fermi momentum values. In addition, a reconstruction of the valence electron charge density distribution via simple expression of the Compton profile is derived.

Tailoring activation of CoNiO nanoparticles/porous carbon nanofibers by atomic doping for high performance supercapacitors.

Metal-organic framework (MOF) materials are rich in active sites and have a high specific surface area, which make them potential electrode materials. In this work, a simple immersion method combined with a carbonization treatment process is applied to prepare MOF derived composite materials (CoNiO/PCNFs). Among them, cobalt-based MOFs (Co-MOFs) are selected as the precursor and doped with Ni atoms, and the ratio of Co and Ni is tailored to acquire a high-performance electrode. The electrochemical results show that when the ratio of Co to Ni is 2 : 2, the prepared CoNiO/PCNFs-2 electrode has high capacitance (912.4 F g-1 at 1 A g-1) and superior rate capability (retention is above 50% at 100 A g-1). Additionally, it is highly stable at 20 A g-1 (nearly no degradation after 6000 cycles). Density Functional Theory (DFT) calculations indicate that the Ni doping models present lower formation energy and better -OH group adsorption properties. Moreover, the density of electronic state (DOS) and differential charge density distribution demonstrate that Ni doping effectively enhances the charge transport during the charging and discharging processes, which is beneficial to enhance the energy storage of the electrode materials. In conclusion, this work presents a strategy to design MOF-derived composite electrodes. The experimental tests and theoretical calculations explore the energy storage process and prove that the CoNiO/PCNF electrode materials have great potential for applications.

First-principles investigation of the structural and dynamical stability, electronic and thermal properties of two-dimensional Yn+1Cn (n = 1, 2, and 3) MXenes

This paper studies the structural and dynamical stability, electronic and thermal properties of two-dimensional Yn+1Cn (n = 1, 2, and 3) MXenes in the hexagonal structure. The calculations are carried out using the computational software package QUANTUM-ESPRESSO/PWSCF based on density functional theory (DFT) and the pseudopotential method. The calculated lattice parameters a and c are in good agreement with the previous theoretical and experimental studies. Structural calculations described that Y4C3 is more stable than Y3C2 and Y2C. Analyzing cohesive energy indicates that the structural stability of these compounds increases with increasing n-index due to the increase in the number of stronger bonds between Y and C atoms in the thicker MXene monolayers. The phonon dispersion calculations show that the Yn+1Cn MXenes are dynamically stable at ambient pressure, and it is possible to be experimentally synthesized.Based on the electronic results, it can be argued that the Yn+1Cn has a metallic behavior in the hexagonal structure. Also, the electron charge density distribution confirms the metallic behavior of Yn+1Cn structures. The thermodynamic calculations indicate that enthalpy increases continuously and steadily by increasing pressure and n-index in the Yn+1Cn structures. Generally, for Yn+1Cn (n = 1, 2, and 3) MXenes with the increasing n-index, Debye temperature and stiffness decrease, followed by heat capacity increases.

Estimating the Ground and Excited State Dipole Moments of Levofloxacin and Norfloxacin Drugs Using Solvatochromic Effects and Computational Work

Levofloxacin (LVF) and norfloxacin (NRF) are a group of fluoroquinolone antibiotics, broad spectrum used to treat various infections caused by many bacterial species. The drugs contain functional groups which control the type and degree of interaction with different solvents. In this research, the ground and excited state dipole moments of LVF and NRF drugs were estimated using solvatochromic effects and computational work. The dipole moments were estimated from absorption and emission spectra in polar and nonpolar solvents using Bakhshiev’s, Kawski–Chamma–Viallet, Lippert–Mataga, and Reichardt models. The results indicated the emission spectra are more strongly affected by solvent polarity than the absorption spectra. The calculated excited state dipole moment is larger than that of the ground state, indicating that the probe compounds are significantly more polarized in the excited state than in the ground state. From computational work, the HOMO-LUMO energy band gap, the dipole moments, electron charge density distribution, and oscillator strength were determined using the semiempirical MP6 method, DFT-B3LYP-6-31G, and DFT-B3LYP-3-21G employing Gaussian 09 software. In general, larger dipole moments were obtained by computation rather than from experiments due to the absence of solvent effects.

Structural and electronic properties of wide band gap charge transfer insulator Hg2Cl2: Insights from the first-principle calculations

The structural and electronic properties of Mercurous Chloride (Hg2Cl2) in its tetragonal (I4/mmm) phase at room temperature have been investigated from the first principle calculations. Detail calculations within the framework of density functional theory (DFT) upon incorporation of spin-orbit coupling (SOC) reveal that Hg2Cl2 is a wide band gap charge transfer (CT) insulator with band gap energy (Eg) ∼ 3.96 eV. Despite being a CT insulator, the orbital resolved PDOS of Hg2Cl2 compound exhibit energy dispositions that do not obey the Zaanen – Sawatzky – Allen (ZSA) diagram. The effect of on-site Coulomb repulsion (Hubbard +Udd) on the band gap of the compound has also been studied in detail. The Mulliken bond population, electronic charge density distribution and Bader charges analyses have been explored to unveil the covalent and ionic interactions between Hg and Cl atoms of the Hg2Cl2 compound. The Natural Bond Orbital (NBO) analyses have been performed to gain deeper insights on the CT interactions between Hg and Cl atoms of Hg2Cl2. The rationale behind the distortions of the octahedral domains within Hg2Cl2 crystal has also been elucidated in detail.

BASIC CONCEPTS IN PSYCHIATRIC GENETICS

We have performed spin-polarized calculation for the electronic band structure, density of states, Fermi surface and the space electronic charge density distribution for the filled-skutterudites LaFe4Pn12 (Pn=P, As and Sb) compounds. It has been noticed that for both LaFe4P12 and LaFe4As12 there are two bands cross Fermi level (EF) for the spin-up and spin-down states, while for LaFe4Sb12 there is only one band cross EF for the spin-up state and three bands cross EF for the spin-down state. As the partial DOS of La-s,d, Fe-s/p/d and Pn-s/p/d coincide Fermi level at nonzero value, it reveals that the electrons of these orbitals contribute in the conduction process. The calculated values of the density of the states at Fermi level N(EF) and the associated electronic specific heat coefficient (γ) for the spin-up/down states are decreases with substituting P→As→Sb. The bonds nature and the interactions between the atoms for the spin-up/down configurations were investigated in (1 0 0) and (1 0 1) crystallographic planes.