Analysis Of Electron Localization Function Research Articles

Ab initio dynamics simulation of laser-induced photodissociation of phenol.

We theoretically investigated the photodissociation dynamics of phenol molecules steered by a sequence of temporally shaped femtosecond laser pulses with high intensity and ultrashort duration, via the real-time Time-Dependent Density Functional Theory (rt-TDDFT) combined with a Molecular Dynamics (MD) simulation. The principal findings of this research are that the phenol photodissociation can take place in 50 fs; the bonds broke sequentially; the degree of phenol molecular dissociation has a strong linear correlation with the intensity. For an incident laser being 800 nm-40 fs (wavelength-pulse duration), the threshold intensity is 7 × 1014 W cm-2 and the products are hydrogen from OH1 (phenolic hydroxyl group) and C6H5O-fragments. More fragments will be found at stronger intensity, shorter wavelengths, and longer pulse duration. More accurately, we estimated the critical values of bond cleavage of an isolated phenol molecule are 1.779 Å for O-H1 and 2.184 Å for C-Hs via Electron localization function (ELF) analysis. The photodissociation of the phenol molecule was triggered via the excitation of electrons and the dissociation process of phenol here is in good agreement with the characteristics of field-assisted dissociation (FAD) theory. Orthogonal tests with an L9 (34) matrix and threshold intensity decrease tests were conducted to confirm the mechanism. Our research gives an insight into the photodissociation experiment of phenol and provides a simple yet effective way to understand the photochemical experiments of more complex organic pollutants with toxicity.

Structure prediction of CuBiI ternary compound and first-principles study of photoelectric properties

Ternary metal halides have attracted much attention as a new potential photoelectric material due to their ultra-high photoelectric conversion efficiencies. In this paper, USPEX, a crystal structure prediction software based on genetic algorithm, is used to investigate the potential crystal structures of ternary CuBiI compounds (CuBi<sub>2</sub>I<sub>7</sub>, Cu<sub>2</sub>BiI<sub>5</sub>, Cu<sub>2</sub>BiI<sub>7</sub>,Cu<sub>3</sub>BiI<sub>6</sub>, Cu<sub>3</sub>Bi<sub>2</sub>I<sub>9</sub>, CuBi<sub>3</sub>I<sub>10</sub>, and Cu<sub>4</sub>BiI<sub>7</sub>) at atmospheric pressure and absolute zero temperature. Based on the density functional theory, the formation energies, elastic coefficients, and phonon dispersion curves of the predicted structures are calculated. The twelve stable CuBiI compounds with good thermodynamic, dynamical and mechanical stabilities are identified. The twelve crystal structures of CuBiI compound feature mainly the co-existence of Cu—I and Bi—I bonds and coordination polyhedrons of I atoms. The band gaps of twelve structures, calculated by HSE06 method, are 1.13–3.09 eV, indicating that the stoichiometric ratio affects the band gap obviously. Among them, the band gaps of Cu<sub>2</sub>BiI<sub>5</sub>-<i>P</i>1, Cu<sub>2</sub>BiI<sub>7</sub>-<i>P</i>1 and Cu<sub>2</sub>BiI<sub>7</sub>-<i>P</i>1-II are relatively small, close to the optimal band gap value for light absorption (1.40 eV), demonstrating that these compounds are suitable for serving as light absorbing materials in solar cells. The distribution of density of state (DOS) indicates that the top of the valence band of CuBiI compound is attributed to the hybridized Cu-3d and I-5p orbitals; the bottom of the conduction band of Cu<sub>3</sub>BiI<sub>6</sub>-<i>R</i>3 comes mainly from the Bi-6p and I-5p orbitals, and Cu-3d contributes little; the conduction band bottom of Cu<sub>2</sub>BiI<sub>7</sub> is mainly from the I-5p orbital, and the Cu-3d has little contribution. The bottoms of the conduction band of other structures originate mainly from the hybridized Bi-6p and I-5p orbitals. Electronic localization function and Bader charge analysis show that the Cu—I and Bi—I bonds have more ionic features and less covalent natures. The DOS distribution also confirms the covalent interaction of Cu/Bi-I. In addition, the CuBiI ternary compounds have extremely strong light absorption capacities (light absorption coefficient higher than 4 × 10<sup>5</sup> cm<sup>–1</sup>) in the high-energy region of visible light and high power conversion efficiency (31.63%), indicating that the CuBiI ternary compounds have the potential to be an excellent photoelectric absorption material. Our investigation suggests the further study and potential applications of CuBiI ternary compound as absorber materials in solar cell.

A theoretical study on novel neutral noble gas compound F4XeOsF4.

A noble gas compound containing a triple bond between xenon and transition metal Os (i.e. F4XeOsF4, isomer A) was predicted using quantum-chemical calculations. At the MP2 level of theory, the predicted Xe-Os bond length (2.407 Å) is between the standard double (2.51 Å) and triple (2.31 Å) bond lengths. Natural bond orbital analysis indicates that the Xe-Os triple bond consists of one σ-bond and two π-bonds, a conclusion also supported by atoms in molecules (AIM) quantum theory, the electron density distribution (EDD) and electron localization function (ELF) analysis. The two-body (XeF4 and OsF4) dissociation energy barrier of F4XeOsF4 is 15.6 kcal mol-1. The other three isomers of F4XeOsF4 were also investigated; isomer B contains a Xe-Os single bond and isomers C and D contain Xe-Os double bonds. The configurations of isomers A, B, C and D can be transformed into each other.

Prediction of beryllium clusters (Ben; n = 3-25) from first principles.

Evolutionary searches using the USPEX method (Universal Structure Predictor: Evolutionary Xtallography) combined with density functional theory (DFT) calculations were performed to obtain the global minimum structures of beryllium (Ben, n = 3-25) clusters. The thermodynamic stability, optoelectronic and photocatalytic properties as well as the nature of bonding are considered for the most stable clusters. It is found that the cluster with n = 15 is the transition point at which the configurations change from 3D hollow cages to filled cage structures (with an interior atom appearing in the structure). All the ground state structures are energetically favorable with negative binding energies, suggesting good synthetic feasibility for these structures. The calculated relative stabilities and electronic structure show that the Be4, Be10 and, Be17 clusters are the most stable structures and can be considered as superatoms. The electron configurations of Be4, Be10 and Be17 clusters with 8, 20 and 34 electrons are identified as 1S2 1P6, 1S2 1P6 1D10 2S2, 1S2 1P6 1D10 2S2 1F14, respectively. Theoretical simulations determined that all the ground state structures exhibit excellent thermal stability, where the upper-limit temperature that the structures can tolerate is 900 K. During AIMD simulation of O2 adsorption onto the Be17 cluster an interesting phenomenon was happening in which the pristine Be17 cluster becomes a new stable Be17O16 cluster. Based on ELF (electron localization function) analysis, it can be concluded that the Be-Be bonds in the small clusters are primarily of van der Waals type, while for the larger clusters, the bonds are of metallic nature. The Ben clusters show very strong absorption in the UV and visible regions with absorption coefficients larger than 105 cm-1, which suggests a wide range of potential advanced optoelectronics applications. The Be17 cluster has a suitable band alignment in the visible-light excitation region which will produce enhanced photocatalytic activities (making it a promising material for water splitting).

Spectroscopic, electron localization function, chemical reactivity and antihypertensive activity study on hordenine alkaloid by density functional theory approach

In the present work, the molecular, electronic and chemical properties of phenylethylamine alkaloid hordenine (HODE) are studied using combined experimental and theoretical methods. The potential energy surface (PES) scan is carried out to identify the stable geometry of the molecule. The optimization of the molecule and vibrational wavenumbers are studied using basis set B3LYP/6-311++G(d,p) for density functional theory calculation. The FT-IR and FT-Raman spectrum of hordenine is recorded in the region 400-4000 cm-1 and 50-3500 cm-1 respectively. Detailed interpretations of the vibrational bands are executed with the help of NCA and the resulting vibrational wavenumbers are scaled by using WLS method. The hyperconjugative interaction, charge delocalization and the stability of the molecule are analyzed using NBO analysis. Reduced density gradient (RDG) analysis is employed to study the weak interactions within the molecule. Electron localization function (ELF) analysis is performed to understand the nature of the chemical bonds in HODE. The 1H and 13C NMR spectra of HODE are recorded and analyzed. UV-visible spectrum of the molecule is recorded and analyzed for the ethanol solvent. MEPS, HOMO, LUMO, global reactivity descriptors and Fukui functions are performed to study the chemical reactivity of the molecule. Hirshfeld surface analysis is performed to analyze the intermolecular interaction in crystal structure. Molecular docking studies are performed to predict the antihypertensive active site of the molecule.

Quantum chemical calculations, spectroscopic properties and molecular docking studies of a novel piperazine derivative

This work is devoted to investigating the molecular geometry, biological activities, electronic and vibrational characteristics of 1-phenylpiperazin-1,4-diium nitrate monohydrate (1PPNO3) by combining quantum chemical calculations with molecular docking. The geometric structure has been optimized with the Density functional theory (DFT) method using B3LYP-D and WB97XD functional. By referring to the values of the RMSD, the DFT calculation reproduces well the bonds lengths and the angles. Atoms-in-molecules, reduced density gradient and electron localization function analyses have been carried out to study the intra and intermolecular interactions within molecule, in particular to study the properties of hydrogen bonds. NBO orbital analysis has been reported to study electronic exchanges and transfer reactions between donor and acceptor compounds. In addition, Hirshfeld Surface Analysis (HS) was evaluated in order to discern the interactions in the crystal structure. The molecular electrostatic potential was calculated to identify the electrophilic and nucleophilic sites which favor the formation of hydrogen bonds. Inhibitor characteristics of 1PPNO3 on Kalirin-7 and monoamine oxidase B enzymes with several selective inhibitors were examined by molecular docking. Finally, thermal (DTA) and thermogravimetric (TG) analyses for the title compound have been conducted and the thermodynamic properties were determined via model chemistry.

A DFT study on the mechanism of the formation of 1,4,2,3‐dithiadiazinanes by head‐to‐head [3 + 3] cyclodimerization of thiocarbonyl S‐imides

AbstractThe possible minimum energy paths (MEP) for the [3 + 3] cyclodimerization (33CD) of thiophosgene S‐imides under formation of tetrachlorodithiadiazinanes are determined with density functional theory (DFT) calculations. Application of the natural bond orbital (NBO) method in combination with electron localization function (ELF) analysis corroborates the experimental observation of the unexpected head‐to‐head 33CD of thiophosgene S‐(N‐arylimides) to form the corresponding 2,3‐diaryl‐5,5,6,6‐tetrachloro‐1,4,2,3‐dithiadiazinanes instead of the isomeric 2,5‐diaryl‐3,3,6,6‐tetrachloro‐1,4,2,5‐dithiadiazinanes. Based on complete active space self‐consistent field (CASSCF) results, delocalized diradicals are postulated as intermediates for the stepwise pseudoradical type formation of the obtained 2,3‐diaryl‐5,5,6,6‐tetrachloro‐1,4,2,3‐dithiadiazinanes, whereby non‐covalent interactions play an important role.

The structural stability, lattice dynamics, electronic, thermophysical, and mechanical properties of the inverse perovskites A 3 OX: A comparative first‐principles study

We present a comparative study on the structural, electronic, elastic, and thermoelectric properties of the cubic inverse-perovskites A3OX (where A = Li, Na, K and X = Cl, Br, I) by density functional theory (DFT). The cohesive, formation, and elastic properties analysis indicates that all studied materials are chemically, thermodynamically, and mechanically stable. Electronic properties reveal that all the inverse A3OX perovskite are direct bandgap semiconductors except Li3OCl and Li3OBr with ionic nature which is confirmed by electron localization function (ELF) analysis. We have also calculated Debye temperature (ΘD) and Grüneisen parameter (γ) to determine the lattice thermal conductivity for all the A3OX materials. Furthermore, thermoelectric (TE) properties are explored by calculating the Seebeck coefficient (S), electronic thermal conductivity, power factor (PF), electrical conductivity (σ/τ), lattice thermal conductivity, and ZT value. Our investigated A3OX inverse-perovskites provide a fertile base that can improve the overall TE performance for TE applications and green energy production.

Theoretical prediction of Xe-containing polymer

ABSTRACT Density functional theory (DFT) calculation has been performed to investigate the C5N4H10XeH2 molecule and Xe-containing polymer CH2Y(XeY)nCH2 (Y = C4N4H8, n = 1∼6). The topological properties at the bond critical point and the electron localisation function analysis show that the Xe-N bond in C5N4H10XeH2 is covalent. Two dissociation channels have been predicted to investigate the stability of C5N4H10XeH2, in which the products of the two-body dissociation channel are Xe and C5N4H12, and the energy barrier is 5.2 kcal mol−1. We also study the CH2Y(XeY)nCH2 polymer, in which Xe is on the one dimensional extension chain. Besides, two one-dimensional chains joined together by Xe associatione, further form two-dimensional network structures. And two network structures with Xe as the skeleton have been optimised by DFT calculation, each of which contains multiple Xe atoms.

A novel quinoxalinedione-bicapped tri-ruthenium carbonyl cluster [Ru3(μ-H)2(CO)6(μ3-HDCQX)2]: synthesis, characterization, anticancer activity and theoretical investigation of Ru–Ru and Ru–Ligand bonding interactions

A new tri-ruthenium dihydrido cluster, [Ru3(μ-H)2(CO)6(HDCQX)2] (1), in which two HDCQX (H2DCQX = 6,7-dichloroquinoxaline-2,3-dione) ligands cap both faces of the tri-ruthenium triangle similarly through oxygen atoms, has been synthesized and characterized by mass, IR, NMR (1H and 13C) and electronic spectroscopy. DFT calculations, in both gas and solution (CPCM/DMSO) phases, were performed to analyze the electronic structure of the cluster and interpret its vibrational and NMR spectra. The presence of non-equivalent bridging hydrides was assigned by 1H NMR as two singlet resonances at δ −16.85 and −17.67 ppm and confirmed by theoretical DFT-GIAO calculations at δ −12.92 and −14.48 ppm. Time-dependent density functional theory (TD-DFT) calculations, performed to characterize the frontier orbitals and interpret the electronic spectrum, indicated that the lowest-energy transition of 1 originates from a highly delocalized HOMO with Ru–Ru (σ), Ru–CO (π) and Ru–CO (σ*) contributions and ends in the LUMO with Ru1–Ru2–Ru3 (σ*) and QX/QX′ (π*) anti-bonding character. The natural transition orbital (NTO) corresponding to this transition revealed a decrease of the electron density on the Ru1Ru2(CO)4 fragment and an increase of the electron density on the Ru1–Ru2–Ru3 unit and the HDCQX ligands. The Ru–Ru and Ru–ligand bonding was studied by the quantum theory of atoms in molecules (QTAIM) and electron localization function (ELF) methods. Both confirmed the presence of unique bonding between the Ru1 and Ru2 atoms and not between Ru3 and the other Ru atoms. While the QTAIM assigned the Ru1–Ru2 bonding as a transit between pure closed-shell and pure shared-shell interactions, the ELF analysis suggested that this bond is dominated by a fluctuation of electron density. The covariance analysis indicated that the core basin populations C(Ru1) and C(Ru2) account for 76% of the V(Ru1, Ru2) variance. Natural bond orbital (NBO) analysis of the Ru3(µ-H)2O4(CO)6 unit indicated a 2c–2e bonding type for the Ru–O, Ru–C and Ru–Ru bonds with orbital occupations of 1.88–1.95, 1.95–1.96, and 1.57 e, respectively, and a 3c–2e bonding for the Ru–H–Ru bonds with an orbital occupation of ca. 1.7 e. NBO second-order perturbative energy analysis was performed to estimate the strength of the Ru–CO π-back-donation and to establish a correlation between the stabilization energy (E(2)) and the spectroscopic data. Although the calculated stabilization energy (E(2)total) follows the expected trend of decreasing the CO stretching frequency (νCO) and increasing the 13CO chemical shift with the extent of the Ru–CO π-back-donation, the latter parameter was more consistent in estimating the strength of such interactions. The in vitro anticancer activities of the title compound and cisplatin were determined against three common types of human cancer cell lines, HCT-116 (colon), HELA (cervix) and MCF-7 (breast). The IC50 values of 3.18 ± 0.40, 4.21 ± 0.29 and 5.39 ± 0.52 μM, respectively, represent 4- and 2-times improvement in potency relative to cisplatin (12.06 ± 1.28, 10.34 ± 2.08 and 6.29 ± 1.68 μM, respectively) against the HCT-116 and HeLa cancer cell lines.

Is It Conjugated or Not? The Theoretical and Experimental Electron Density Map of Bonding in p-CH3CH2COC6H4-C≡C-C≡C-p-C6H4COCH3CH2.

The electron density of p-CH3CH2COC6H4-C≡CC≡C-p-C6H4COCH3CH2 has been investigated on the basis of single-crystal X-ray diffraction data collected to high resolution at 100 K and from theoretical calculations. An analysis of the X-ray data of the diyne showed interesting “liquidity” of electron distribution along the carbon chain compared to 1,2-diphenylacetylene. These findings are compatible with the results of topological analysis of Electron Localization Function (ELF), which has also revealed a larger (than expected) concentration of the electron density at the single bonds. Both methods indicate a clear π-type or “banana” character of a single bond and a significant distortion from the typical conjugated structure of the bonding in the diyne with a small contribution of cumulenic structures.

A topological study of the haxacoordinated carbon in the pentagonal-pyramidal benzene and hexamethylbenzene dications

The nature of the hexacoordinated carbon in the pentagonal-pyramidal benzene and hexamethylbenzene dications was investigated using the Atoms in Molecules (AIM’s analysis) and the electron localization function (ELF) analysis. The following conclusions were reached from the AIM analysis: (i) six bond critical points linked to the apical carbon atom were found; (ii) at the equilibrium geometry, no cage critical point was observed; and (iii) Bader’s charges are consistent with a cyclopentadiene cation linked to a [C-R]+ fragment. The topological analysis of the ELF shows a near ring basin between the apical carbon and the pentadiene ring.

SF6 Decomposition Gas Sensor Based on GeP Monolayer: A First-Principle Study

In this paper, we adopted the first-principles calculations to investigate the sensing properties of the GeP monolayer to four SF6 decomposition gas molecules (H2S, SO2, SO2F2 and SOF2). By discussing the calculated adsorption energy, charge transfer, work function variation combined with charge density difference and electron localization function analysis, we find that GeP monolayer exhibits favorable adsorption strength to SO2 molecule with the most intense charge interaction. And SO2 adsorption can remarkably change the density of states (DOS) of GeP monolayer. Furthermore, we also study the adsorption performance of SO2 molecule on GeP monolayer under applied biaxial strain and external electric field. And the results demonstrate that applying negative electric field can significantly enhance the sensitivity of GeP monolayer to SO2. Therefore, GeP monolayer is a potential candidate for highly sensitive and selective tunable SF6 decomposition gas sensor for on-line diagnostics of power equipment.

Spectroscopic elucidation (FT-IR, FT-Raman and UV-visible) with NBO, NLO, ELF, LOL, drug likeness and molecular docking analysis on 1-(2-ethylsulfonylethyl)-2-methyl-5-nitro-imidazole: An antiprotozoal agent

1-(2-ethylsulfonylethyl)-2-methyl-5-nitro-imidazole (1EMI) C8H13N3O4S also known as Tinidazole, selected for its antiprotozoal property is extensively used for spectroscopic elucidations and computational aspects using density functional methods. Along with spectral conclusions, further investigations on fundamental reactive properties such as electrical, optical, nonlinear combined with DFT simulations were performed. Molecular docking procedure supports the results of chosen appropriate antiprotozoal agent based on ligand-protein interactions. Experimental and simulated (B3LYP/6-311++G (d,p)) IR and Raman spectra showed concurrence. NLO analysis through first order hyperpolarizability parameter helps in finding the potential of 1EMI as a good NLO candidate. Charge delocalization and the stability of the compound were discussed using natural bond orbital (NBO) analysis. Furthermore, Electron localization function (ELF), local orbital locator (LOL), and Frontier molecular orbitals (FMO) were studied. Besides, Mulliken population analysis on atomic charges, Energy gap, chemical potential, global hardness, softness, ionization potential, electronegativity, electrophilicity index along thermodynamic parameters (enthalpy, entropy and heat capacity) have been calculated. Drug likeness parameters and molecular docking approach enabled to check pharmaceutical potential and biological activity of 1EMI. The biological activity of 1EMI through ligand and protein interactions have been confirmed theoretically for the treatment of Malaria, Invasive aspergillosis and Mycobacterium tuberculosis with respect to chosen proteins. Three different activity targets and protein interactions are quite successful revealing the bond distances, intermolecular energy, binding energy and inhibition constant. 2D interaction profile image of the two maximum interacted proteins and also Ramachandran plot used to show stereochemistry of selected protein. The activities of 1EMI were studied in accordance with literature survey and the results were presented.

The nature of the triple B[tbnd]B, double, B[dbnd]B, single, B–B, and one-electron, B.B boron-boron bonds from the topological analysis of electron localisation function (ELF) perspective

Local nature of the boron-boron (BB) bond has been investigated in 23 molecules using the topological analysis of Electron Localisation Function (ELF) and the electron density (AIM) frameworks. The wave function has been approximated using the CCSD//CCSD(T), CASSCF and DFT(M062x) methods and triple-zeta basis sets. The calculations yielded a formally triple bond, BB, with population of 5.87–4.67e, a double bond BB with population of 4.39–3.58e, a single bond, B–B with population of 2.49–2.04e and one electron bond, B.B with 0.38e. Topological analysis of ρ(r) field has shown the non-nuclear attractor, NNA, for the BB bond in ten molecules (CCSD, DFT) with ropt(B,B) smaller than 1.6 Å. Population of the pseudo-atom basin ranges from 0.28e to 1.42e (CCSD) and from 0.32e to 1.27e (DFT). An overview of the results from topological analysis of ELF together with a detailed discussion of electronic structure for 14 small molecules has been presented.

Discerning the thermal cyclotrimerizations of fluoro- and chloroacetylenes through ELF, NBO descriptors and QTAIM analysis: pseudodiradical character

In this study the thermal cyclotrimerization reactions of fluoro- and chloroacetylenes involving regioselectively stepwise {2 + 2} and stepwise {4 + 2} cycloadditions were studied using the topological analysis of the electron localization function (ELF), the quantum theory of atoms in molecules (QTAIM) and natural bond orbital (NBO) analyses. These methodologies have shown that the electronic reorganization in the regioselectively stepwise {2 + 2} and stepwise {4 + 2} cycloadditions may be considered as {2n+2n} and {2π+2n} pseudodiradical process, respectively. Finally, the last phase of this thermal reaction can be understood as an electronic migration process under the pseudodiradical character in the thermal ring-opening reaction, with the subsequent formation of reaction products. In this sense, new insights are reported on the electronic behavior in the bond formation in the thermal cyclotrimerization of fluoroacetylene.

New boron-capped cage manganese(II) complex with terminal thiophene-2-carboxaldehyde groups: Crystal structure and density functional theory investigation for electron transfer

A metal-containing clathrochelate complex [Mn2II(hmbd)3[(5–ftba)2]·Et3NH·CH3OH has been synthesized with 2-hydroxy-5-methyl-1,3-benzenedicarboxaldehyde dioxime (abbreviated as H3hmbd) and 5-formyl-2-thiopheneboronic acid (abbreviated as 5-ftba) by template method and characterized by elemental analysis, IR spectra, MS and single-crystal X-ray diffraction. Density functional theory (DFT) calculations have been performed to further understand the geometry, electronic structure and nature of electron transfer under various electric fields. Mayer bond order (MBO) analysis, electron localization function (ELF) analysis and atoms in molecules (AIM) analysis were carried out to study the electronic structure and the structural stability under applied electric fields. The deviation of natural population analysis (NPA) charge together with the charge density difference (CDD) plots in various electric fields was plotted to research the electron transfer process under applied electric fields. The density of states (DOS) analysis, distribution of highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO), the energy of the HOMO-LUMO gap (HLG) analysis were investigated to reveal the nature of electron transfer under the applied electric field.

The Role of the Interactions at the Tungsten Disulphide Surface in the Stability and Enhanced Thermal Properties of Nanofluids with Application in Solar Thermal Energy.

Transition metal dichalcogenides (TMCs) exhibit unique properties that make them of interest for catalysis, sensing or energy storage applications. However, few studies have been performed into nanofluids based on TMCs for heat transfer applications. In this study, nanofluids based on 2D-WS2 are prepared by liquid phase exfoliation to analyze their potential usage in concentrating solar power plants. Periodic-Density Functional Theory (DFT) calculations were performed to rationalize the success of the exfoliation process. The hydrogen bond interaction between the hydroxyl group from PEG, which acts as a surfactant, and the S atoms of the WS2 surface stabilizes the nanosheets in the fluid. Electron localization function (ELF) analysis is indicative of the stability of the S–H interaction from WS2 with the molecules of surfactant due to the tendency to interact through weak intermolecular forces of van der Waals solids. Moreover, improvements in thermal properties were also found. Isobaric specific heat increased by up to 10% and thermal conductivity improved by up to 37.3%. The high stability of the nanofluids and the thermal improvements were associated with the high surface area of WS2 nanosheets. These results suggest that these nanofluids could be a promising heat transfer fluid in concentrating solar power plants.

The nature of multiple boron-nitrogen bonds studied using electron localization function (ELF), electron density (AIM), and natural bond orbital (NBO) methods

Local nature of the boron-nitrogen (BN) bonding with different formal multiplicities (B≡N, B=N, B-N) have been investigated for 25 experimentally established organoboron molecules in both real and the Hilbert space, using topological analysis of electron localization function (ELF), electron density (AIM), and natural bond orbital (NBO) method. Each BN bond has been represented (ELF) by the bonding disynaptic attractor V(B,N), with the basin electron population between 5.72e and 1.83e, confirming possible existence of all the three bond types. A covalent character of bonding can be associated with the dative mechanism due to the V(B,N) bonding basin formed mainly (91–96%) by the N electron density. Similarly, the NBO method shows 2-center natural orbitals, consisting largely of the hybrids from the N atom. The AIM analysis yields the features typical for shared (H(3,−1)(r) < 0) and closed-shell (∇2ρ(3,−1)(r) > 0) interactions. The delocalization indices, describing electron exchanges between B and N quantum atoms, are smaller than 1.5, even for formally very short triple B≡N bonds.Graphical abstract.

Computational Evidence for Homonuclear GeIGeI Dative Bonds.

Dative bonds between identical atoms of the same formal oxidation state are formed as geometric and electronic constraints turn an otherwise lone pair into a bond. Calculations at the B3LYP/6-31+g(d,p) level supported by additional atoms in molecules (AIM) and electron localization function (ELF) analyses on selected germanium polycations are used to prove the concept. The electron density (ρ) is not equally shared between the two atoms of such a homonuclear dative bond (HDB), and the associated charge transfer results in formal charges contradicting chemical convention.