We present a tight-binding model which goes beyond the traditional two-center approximation and allows hopping parameters repulsive energy to be dependent on binding environment. Using carbon as an example, we show that approach improves remarkably transferability of model. The properties higher-coordinated metallic structures are well described by in addition those lower-coordinated covalent structures. \textcopyright{} 1996 American Physical Society.

Coupled-cluster (CC) methods have been extensively used as the high-level approach in quantum electronic structure theory to predict various properties of molecules when experimental results are unavailable. It is often assumed that CC methods, if they include at least up connected-triple-excitation quasiperturbative corrections a full treatment single and double excitations (in particular, CCSD(T)), very large basis set, more accurate than Kohn-Sham (KS) density functional (DFT). In present...

One of the greatest challenges for theoretical study transition-metal-containing compounds is treatment intrinsically multiconfigurational atoms and molecules, which require a multireference (MR) in wave function theory. The accuracy density functional theory such systems still being explored. Here, we continue that exploration by presenting predictions 42 exchange-correlation (xc) functionals 11 types [local spin approximation (LSDA), generalized gradient (GGA), nonseparable (NGA),...

A water-soluble rhodamine-based derivative (L) has been rationally designed for selective recognition of Al3+ in aqueous medium with good sensitivity. The addition to the solution L induces a remarkable fluorescence enhancement along obvious color change detected by naked eye, due ring-opening mechanism rhodamine spirolactam, which proved single crystal diffraction analyses directly. recognizing behavior investigated both experimentally and computationally. Furthermore, fluorescent probe can...

A new C3-symmetric Schiff-base fluorescent probe (L) based on 8-hydroxy-2-methylquinoline has been developed. As expected, the L can display high selectivity for Cd2+ over Zn2+ and most other common ions in neutral ethanol aqueous medium. Moreover, mechanism of L–Cd2+ complex confirmed by X-ray crystallography density functional theory calculation results. More importantly, could be used to image within living cells.

A polyoxometalate-templated silver thiolate nanocluster, [Ag62(StBu)40(Mo20O66)(Mo6O19)3(CH3CN)2]·(CF3SO3)4 (1), has been isolated, in which a giant peanut-like silver(I)-thiolate cluster [Ag62(StBu)40]22+ encapsulates an unprecedented [Mo20O66]12− polyoxoanion core. It opens new approach for the synthesis of both elusive polyoxometalates and high-nuclearity nanoclusters.

Two chiral three-dimensional (3-D) coordination polymers, [Cd4(μ3-HPhIDC)2(μ4-HPhIDC)2(H2O)] (1) and two achiral 3-D [Mn1.5(μ3-PhIDC)(H2O)3] (2) [Mn(μ3-HPhIDC)(H2O)]2} (3), have been synthesized by hydro(solvo)thermal reaction, employing 2-phenyl-1H-imidazole-4,5-dicarboxylic acid (H3PhIDC) as organic ligand, characterized single-crystal X-ray diffraction, elemental analyses, IR spectra. Polymer 1 crystallizes in the orthorhombic space group P2(1)2(1)2(1) exhibits a framework, which...

Herein, a mechanism of stepwise metal-center exchange for specific metal-organic framework, namely, [Zn4 (dcpp)2 (DMF)3 (H2 O)2 ]n (H4 dcpp=4,5-bis(4'-carboxylphenyl)phthalic acid), is disclosed the first time. The coordination stabilities between central metal atoms and ligands as well geometry are considered to be dominant factors in this mechanism. A new magnetic analytical method theoretical model confirmed that reasonable. When metathesis reaction occurs Cu(II) ions framework Zn(II)...

Der Schweratomeffekt kann den Unterschied in nichtlinearen optischen Eigenschaften dritter Ordnung der Cluster [Ag10(dcapp)4](OH)2⋅12 H2O (1, siehe Struktur), [Zn4O(dcapp)3]⋅6 (2) und [Hg2(dcapp)2] (3) nicht erklären (H2dcapp=2,6-Dicarboxamido-2-pyridylpyridin). Quantenchemischen Rechnungen zufolge werden die NLO-Eigenschaften von 1 durch das Metall Liganden beeinflusst, 2 3 nur Liganden.

Six triangular silver(I) or gold(I) 4-chloro/iodo-3,5-diphenyl pyrazolates, as well a 4-methyl-3,5-diphenyl pyrazolate, have been synthesized and structurally characterized by single-crystal X-ray diffraction. Comparison inspection of the Ag/Au⋯Cl/I distances, geometries C–Cl/I bonds with respect to Ag3 Au3 triangles, crystal packing diagrams verify existence Ag3⋯Cl/I Au3⋯I interactions in some structures trimers, which are strong enough impart substantial effect on spatial arrangement...

Vanadium dimer is a notoriously difficult case for Kohn–Sham (KS) density functional theory with currently available approximations to the exchange–correlation (xc) functionals, and many approximate xc functionals yield an exceedingly large error in calculated bond energy. In this paper, we first test energies estimated by 43 Hartree–Fock (HF) method. The results further confirm errors show that, experimental energy being 64.2 kcal/mol, KS calculations give predictions all over map ranging...

Emergence is a common phenomenon, and it also general important concept in complex dynamic systems like artificial societies. Usually, societies are used for assisting resolving several social issues (e.g., emergency management, intelligent transportation system) with the aid of computer science. The levels an emergence may have effect on decisions making, occurrence degree generally perceived by human observers. However, due to ambiguity inaccuracy observers, propose quantitative method...

Geometry optimizations and vibration frequencies of B4C clusters were performed with Becke-3LYP method using 6-31G(d) basis set. We have found 14 stable isomers, the most structure among them is five-member ring containing two three-member boron rings. also analyzed these isomers in detail, results show that structures rings are predominant energy for clusters. In terms MO NBO analysis, three-centered bond pi-electron delocalization play an important role stabilizing planar Our calculations...

The growing design-productivity gap has made designers shift toward using high-level synthesis (HLS) techniques to generate register transfer level design from languages. Unfortunately, this translation process is very complex and may introduce bugs into the generated design, which can create a mismatch between what designer intends actually implemented in circuit. In paper, we present an equivalence checking method validate result of HLS scheduling against initial program. Finite state...

In order to select effective policies for emergency management in a timely manner, this paper proposes an agile and lightweight social computing approach facilitating policy selection, evaluation, adjustment relative both quantitative qualitative ways. The consists of three components represented as PZE: 1) (P) selecting; 2) (Z) modeling artificial societies with the zombie-city model (a general formal society model); 3) (E) evaluation. specification rigorous expressions scenarios enable...

Water–benzene interactions are investigated in a metal–organic framework incorporating strong H-bond nets which contribute to distinct proton conduction.

Abstract Geometry optimizations and vibrational frequencies of B 5 C clusters were calculated with the Becke‐3LYP method using 6‐311+G(d) basis set some stable configurations have been found. The most structure is a planar six‐membered ring. However, for clusters, linear boron atom in position 3. Various containing three‐membered rings predominance energy, whereas various carbon are disadvantageous energy. In isomer2 can be converted into isomer1 by surmounting an energy barrier 43.83 kJ.mol...