scholarly journals AIM and ELF bonding analyses of M–O and M–N (Metal= Ba, Y, Zr) in metal–complexes using DFT approach

2021 ◽  
Vol 15 (1) ◽  
pp. 90
Author(s):  
Nor Ain Fathihah Abdullah ◽  
Sharizal Hasan ◽  
Sin Ang Lee
Keyword(s):  
Density Functional Theory ◽  
Critical Point ◽  
Density Functional ◽  
Chelating Agents ◽  
Ionic Character ◽  
Bond Critical Point ◽  
Electron Localization ◽  
Functional Theory ◽  
Total Electron ◽  
Ionic Bonding

The molecular interaction between the chelating agents of citric acid (CA), ethylenediaminetetraacetic acid (EDTA), and triethylenetetraamine (TETA) with metals (M = Ba, Y, and Zr) were studied using Density Functional Theory (DFT) method. This study aims to determine the type of bonding between M–O/N bonds in the CA/EDTA/TETA– complexes. In this study, each metal was attached at strategic positions of chelating agents and was optimized at B3LYP/6-31G* and UGBS level of theory. The M–O bonds were characterized based on Atoms–in–molecules (AIM) and Electron Localization Function (ELF) in the topological analysis. In AIM analysis, the total electron energy density at the bond critical point (BCP) of the M–O/N bonds are used to estimate the interaction involved. The low values of ρ(r) and positive values of ∇2ρ(r) indicates that ionic character exists in the M–O/N bonds. In ELF color-filled map, the blue shaded region between M–O/N atom acts as an indicator for the existence of the ionic interaction. Both AIM and ELF results confirm the existence of ionic bonding between M–O/N bonds, with values of ρ(r) and ∇2ρ(r) ranging from 0.02 to 0.12 au and 0.09 to 0.5 au respectively. Further analysis on charge distribution at M–O/N bonds show that the opposite charge between Ba, Y, and Zr with O/N assured the M–   O/N ionic bonding interactions. Keywords: Density functional theory, metals, bonding, atom–in–molecules, bond critical point, electron localization functions

scholarly journals A family of ionic supersalts with covalent-like directionality and unconventional multiferroicity

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yaxin Gao ◽  
Menghao Wu ◽  
Puru Jena
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Building Blocks ◽  
Cluster Ions ◽  
Ionic Crystals ◽  
Functional Theory ◽  
Reversible Strain ◽  
Ionic Bonding ◽  
Cluster Ion ◽  
Ferroelectric Switching

AbstractIonic crystals composed of elemental ions such as NaCl are non-polar due to directionless ionic bonding interactions. Here, we show that these can develop polarity by changing their building blocks from elemental ions to superalkali and superhalogen cluster-ions, which mimic the chemistry of alkali and halogen atoms, respectively. Due to the non-spherical geometries of these cluster ions, corresponding supersalts form anisotropic polar structures with ionic bonding, yet covalent-like directionality, akin to sp3 hybridized systems. Using density functional theory and extensive structure searches, we predict a series of stable ferroelectric/ferroelastic supersalts, PnH4MX4 (Pn = N, P; M = B, Al, Fe; X = Cl, Br) composed of superalkali PnH4 and superhalogen MX4 ions. Unlike traditional ferroelectric/ferroelastic materials, the cluster-ion based supersalts possess ultra-low switching barrier and can endure large ion displacements and reversible strain. In particular, PH4FeBr4 exhibits triferroic coupling of ferroelectricity, ferroelasticity, and antiferromagnetism with controllable spin directions via either ferroelastic or 90-degree ferroelectric switching.

scholarly journals Μελέτη της δομής και της φυσικοχημικής συμπεριφοράς μέταλλο-υποκατεστημένων αρενίων με μέταλλα της 11ης ομάδας

2017 ◽  
Author(s):  
Δημήτριος Γκαρμπούνης
Keyword(s):  
Density Functional Theory ◽  
Chemical Shift ◽  
Density Functional ◽  
Natural Bond Orbital ◽  
Electron Localization ◽  
Functional Theory ◽  
Nucleus Independent Chemical Shift ◽  
Reduced Density Gradient ◽  
Reduced Density ◽  
Homo Lumo

Στην παρούσα διατριβή μελετήθηκε μια σειρά υποκατεστημένων βενζολικών δακτυλίων με άτομα μετάλλων νομισματοκοπείου του γενικού τύπου C6H6-nMn (M = Cu, Ag, Au, n = 1 – 6), με τη βοήθεια της μεθόδου συναρτησιακού πυκνότητας (Density Functional Theory), που χαρακτηρίζεται με το ακρώνυμο DFT. Συγκεκριμένα μελετήθηκαν διεξοδικά τόσο οι δομικές όσο και οι ενεργειακές, μαγνητοτροπικές και φασματοσκοπικές ιδιότητες των παραπάνω ενώσεων και συγκρίθηκαν με τις αντίστοιχες ιδιότητες του μη υποκαταστημένου αρωματικού βενζολικού δακτυλίου. Σε αντίθεση με τον βενζολικό δακτύλιο, τα μεταλλουποκαταστημένα βενζόλια του τύπου C6H6-nMn (M = Cu, Ag, Au, n = 1 – 6) παρουσιάζουν αρωματικό χαρακτήρα ακόμα και στην τριπλή διεγερμένη κατάστασή τους. Από τη μελέτη αυτή προέκυψαν πολύ καλές γραμμικές συσχετίσεις του τανυστή zz στο σημείο 1, NICSzz(1), του δείκτη αρωματικότητας NICS (Nucleus Independent Chemical Shift), 1) με το συνολικό αρνητικό φυσικό φορτίο που φέρει ο καρβοκυκλικός δακτύλιος και 2) με το μήκος κύματος (λ) της μετάπτωσης HOMO → LUMO στα φάσματα απορρόφησης των ενώσεων C6H6-nMn. Τα φάσματα εκπομπής των ενώσεων C6H6-nMn χαρακτηρίζονται από τις υψηλές τιμές της διαφοράς ενέργειας ΔE(S0-T1) ειδικά στις περιπτώσεις των δι-υποκατεστημένων μέτα- και πάρα- ισομερών. Η μέγιστη τιμή ΔE(S0-T1) που υπολογίστηκε για την ένωση m-C6H4Au2 είναι ίση με 67 kcal/mol. Μελετήθηκαν επίσης τα δεσμικά χαρακτηριστικά των μετάλλων Cu, Ag, Au με τους βενζολικούς δακτυλίους για κάθε περίπτωση, με τη βοήθεια διαφόρων υπολογιστικών κβαντοχημικών μεθόδων, όπως είναι η πλυθησμιακή ανάλυση φυσικών τροχιακών δεσμού (Natural Bond Orbital, NBO), η πλυθησμιακή ανάλυση με τη μέθοδο των Ατόμων-Στα-Μόρια (Atoms-In-Molecules, AIM), τη συνάρτηση ηλεκρονιακού εντοπισμού (Electron Localization Function, ELF), την κλίση ανηγμένης πυκνότητας (Reduced Density Gradient, RDG) και οι συναρτήσεις Sign(λ2(r))ρ(r) για ακόμα μεγαλύτερη ακρίβεια. Η θεωρητική μελέτη των ενώσεων C6H6-nMn (M = Cu, Ag, Au, n = 1 – 6) έδειξε ότι αυτές είναι θερμοδυναμικά σταθερές και κατά συνέπεια θα ήταν δυνατή η σύνθεση και απομόνωσή τους από πειραματικούς χημικούς.Επίσης, μελετήθηκε, με μεθόδους της DFT, η ικανότητα αντιπρωσοπευτικών ενώσεων, όπως του C6H5Cu και 1,3,5-Cu3C6H3 για τη δέσμευση και αποθήκευση μοριακού υδρογόνου και βρέθηκε να τηρούν τις απαιτήσεις του US DOE για χαμηλού κόστους υλικών αποθήκευσης υδρογόνου. Μια εμπεριστατωμένη ανάλυση των δεσμικών Cu∙∙∙(η2-H2) αλληλεπιδράσεων με τη βοήθεια υπολογιστικών μεθόδων ηλεκτρονικής δομής (NBO, AIM, ELF, RDG και συναρτήσεων Sign(λ2(r))ρ(r)) έδειξε ότι οι αλληλεπιδράσεις αυτές εμφανίζουν έναν μικτό ομοιοπολικό - ιοντικό χαρακτήρα που συνοδεύεται από ασθενείς διαμοριακές αλληλεπιδράσεις διασποράς.

scholarly journals Electronic Transport in the V-Shaped Edge Distorted Zigzag Graphene Nanoribbons with Substitutional Doping

2019 ◽  
Vol 2019 ◽  
pp. 1-8
Author(s):  
Nguyen Thanh Tien ◽  
Nguyen Van Ut ◽  
Bui Thai Hoc ◽  
Tran Thi Ngoc Thao ◽  
Nguyen Duy Khanh
Keyword(s):  
Density Functional Theory ◽  
Electronic Transport ◽  
Transmission Spectrum ◽  
Density Functional ◽  
Graphene Nanoribbons ◽  
Electron Localization ◽  
Functional Theory ◽  
Substitutional Doping ◽  
Electronic Nanodevices ◽  
Zigzag Graphene Nanoribbons

Density-functional theory (DFT) in combination with the nonequilibrium Green’s function formalism is used to study the effect of substitutional doping on the electronic transport properties of V-shaped edge distorted zigzag graphene nanoribbons (DZGNRs), in which DZGNRs with the various widths of four-, six-, and eight-zigzag chains are passivated by H atoms. In this work, Si atoms are used to substitute carbon atoms located at the center of the samples. Our calculated results have determined that Si can change the material type by the number of dopants. We found that the transmission spectrum strongly depends on the various widths. The width of eight-zigzag chains exhibits the largest transmission among four- and six-zigzag chains, and the single Si substitution presents larger transmission than the double case. The obtained results are explained in terms of electron localization in the system due to the presence of distortion at edge and impurities. The relationships between the transmission spectrum, the device density of states, and the I-V curves indicate that DZGNRs are the highly potential material for electronic nanodevices.

scholarly journals Electron Localization in Defective Ceria Films: A Study with Scanning-Tunneling Microscopy and Density-Functional Theory

2011 ◽  
Vol 106 (24) ◽  
Author(s):  
Jan-Frederik Jerratsch ◽  
Xiang Shao ◽  
Niklas Nilius ◽  
Hans-Joachim Freund ◽  
Cristina Popa ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Scanning Tunneling Microscopy ◽  
Density Functional ◽  
Scanning Tunneling ◽  
Electron Localization ◽  
Tunneling Microscopy ◽  
Functional Theory

scholarly journals DFT Study of the Molecular and Electronic Structure of Metal-Free Tetrabenzoporphyrin and Its Metal Complexes with Zn, Cd, Al, Ga, In

2022 ◽  
Vol 23 (2) ◽  
pp. 939
Author(s):  
Alexey V. Eroshin ◽  
Arseniy A. Otlyotov ◽  
Ilya A. Kuzmin ◽  
Pavel A. Stuzhin ◽  
Yuriy A. Zhabanov
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Electronic Absorption Spectra ◽  
Nbo Analysis ◽  
Molecular Structures ◽  
Basis Set ◽  
Ionic Character ◽  
Functional Theory ◽  
Metal Free ◽  
Zinc Cadmium

The electronic and molecular structures of metal-free tetrabenzoporphyrin (H2TBP) and its complexes with zinc, cadmium, aluminum, gallium and indium were investigated by density functional theory (DFT) calculations with a def2-TZVP basis set. A geometrical structure of ZnTBP and CdTBP was found to possess D4h symmetry; AlClTBP, GaClTBP and InClTBP were non-planar complexes with C4v symmetry. The molecular structure of H2TBP belonged to the point symmetry group of D2h. According to the results of the natural bond orbital (NBO) analysis, the M-N bonds had a substantial ionic character in the cases of the Zn(II) and Cd(II) complexes, with a noticeably increased covalent contribution for Al(III), Ga(III) and In(III) complexes with an axial –Cl ligand. The lowest excited states were computed with the use of time-dependent density functional theory (TDDFT) calculations. The model electronic absorption spectra indicated a weak influence of the nature of the metal on the Q-band position.

scholarly journals Comparison Between Electride Characteristics of Li3@B40 and Li3@C60

2021 ◽  
Vol 9 ◽  
Author(s):  
Prasenjit Das ◽  
Pratim Kumar Chattaraj
Keyword(s):  
Density Functional Theory ◽  
Catalytic Activity ◽  
Small Molecules ◽  
Electron Density ◽  
Density Functional ◽  
Nonlinear Optical ◽  
Electron Localization ◽  
Functional Theory ◽  
Density Analysis ◽  
Electron Density Analysis

Density functional theory (DFT) based computation is performed on the endohedrally encapsulated Li3 cluster inside the B40 and C60 cages namely, Li3@B40 and Li3@C60. For both these systems, the Li-Li bond lengths are shorter than that in the free Li3 cluster. Due to confinement, the Li-Li vibrational frequencies increase in both the systems as compared to that in the free Li3 cluster. Thermodynamically, the formation of these two systems is spontaneous in nature as predicted by the negative values of Gibbs’ free energy changes (ΔG). For both the systems one non-nuclear attractor (NNA) is present on the middle of the Li3 cluster which is predicted and confirmed by the electron density analysis. The NNA population and the percentage localization of electron density at the NNA of the Li3@C60 system are higher than that in the Li3@B40 system. At the NNA the values of the Laplacian of electron density are negative and an electron localization function basin is present at the center of the Li3 cluster for localized electrons. Both systems show large values of nonlinear optical properties (NLO). Both the Li3 encapsulated endohedral systems behave as electrides. Electrides have low work function and hence have a great potential in catalytic activity toward the activation of small molecules (such as CO2, N2). Even some electrides have greater catalytic activity than some well-studied metal-loaded catalysts. As the systems under study behave as electrides, they have the power to show catalytic activity and can be used in catalyzing the activation of small molecules.

scholarly journals Li and Na Adsorption on Graphene and Graphene Oxide Examined by Density Functional Theory, Quantum Theory of Atoms in Molecules, and Electron Localization Function

Molecules ◽  
2019 ◽  
Vol 24 (4) ◽  
pp. 754 ◽  
Author(s):  
Nicholas Dimakis ◽  
Isaiah Salas ◽  
Luis Gonzalez ◽  
Om Vadodaria ◽  
Korinna Ruiz ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Graphene Oxide ◽  
Quantum Theory ◽  
Density Functional ◽  
Electron Localization Function ◽  
Electron Localization ◽  
Functional Theory ◽  
Localization Function ◽  
Metal Metal ◽  
Metal Bonds

Adsorption of Li and Na on pristine and defective graphene and graphene oxide (GO) is studied using density functional theory (DFT) structural and electronic calculations, quantum theory of atoms in molecules (QTAIM), and electron localization function (ELF) analyses. DFT calculations show that Li and Na adsorptions on pristine graphene are not stable at all metal coverages examined here. However, the presence of defects on graphene support stabilizes both Li and Na adsorptions. Increased Li and Na coverages cause metal nucleation and weaken adsorption. Defective graphene is associated with the presence of band gaps and, thus, Li and Na adsorptions can be used to tune these gaps. Electronic calculations show that Li– and Na–graphene interactions are Coulombic: as Li and Na coverages increase, the metal valences partially hybridize with the graphene bands and weaken metal–graphene support interactions. However, for Li adsorption on single vacancy graphene, QTAIM, ELF, and overlap populations calculations show that the Li-C bond has some covalent character. The Li and Na adsorptions on GO are significantly stronger than on graphene and strengthen upon increased coverages. This is due to Li and Na forming bonds with both carbon and oxygen GO atoms. QTAIM and ELF are used to analyze the metal–C and metal–metal bonds (when metal nucleation is present). The Li and Na clusters may contain both covalent and metallic intra metal–metal bonds: This effect is related to the adsorption support selection. ELF bifurcation diagrams show individual metal–C and metal–metal interactions, as Li and Na are adsorbed on graphene and GO, at the metal coverages examined here.

Nonperturbative time-dependent density functional theory (TDDFT) and time-dependent electron localization function (TDELF) study of the ionization of OCS and CS2 with ultrashort intense laser pulses — Orientational effects

2012 ◽  
Vol 90 (7) ◽  
pp. 616-624 ◽  
Author(s):  
Emmanuel Fowe Penka ◽  
André Dieter Bandrauk
Keyword(s):  
Density Functional Theory ◽  
Laser Pulse ◽  
Density Functional ◽  
Laser Pulses ◽  
Time Dependent ◽  
Intense Laser ◽  
Electron Localization ◽  
Functional Theory ◽  
Intense Laser Pulses ◽  
Dependent Density

The nonlinear nonperturbative response of OCS and CS2 to ultrashort (few cycles) intense laser pulses was studied numerically by time-dependent density functional theory (TDDFT) methods to understand molecular ionization as a function of laser–molecule orientation. A time-dependent electron localization function(TDELF) was used to visualize the nonlinear nonperturbative electron transfer occurring during the laser pulse. It was found that, for intensities I > 3.5 × 1014 W/cm2, the inner shell Kohn–Sham (KS) molecular orbitals contribute significantly to the ionization, whereas for the intensity I < 3.5 × 1014 W/cm2, the highest occupied molecular orbital (HOMO) shows the dominant response to the field. In general, the ionization rate maxima correspond to the alignment of maximum KS orbital densities with the laser pulse polarization instead of orbital ionization potentials (IP). These findings are corroborated through analysis of the TDELF images, where the ionization occurs from the lone pair or bond regions of the corresponding molecules.

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