We present a generalized energy-based fragmentation (GEBF) approach for approximately predicting the ground-state energies and molecular properties of large molecules, especially those charged polar molecules. In this approach, total energy (or properties) molecule can be obtained from calculations on various small subsystems, each which is constructed to contain certain fragment its local surroundings within given distance. quantum chemistry calculation subsystem, distant atoms (outside...

The chain length dependence of excitation energies oilgomers polyene, p-phenylene, pentafulvene, cyclopentadiene, pyrrole, furan, silole, phosphole, and thiophene was studied employing the time-dependent density functional theory with B3LYP functional. Band gaps effective conjugation lengths corresponding polymers were obtained by extrapolating vertical trimers through pentamers to infinite length. Polypentafulvene, polycyclopentadiene, polysilole, polyphosphole predicted have smaller band...

A linear scaling local correlation approach is proposed for approximately solving the coupled cluster doubles (CCD) equations of large systems in a basis orthogonal localized molecular orbitals (LMOs). By restricting double excitations from spatially close occupied LMOs into their associated virtual LMOs, number significant excitation amplitudes scales only linearly with size molecules. Significant are obtained to very good approximation by CCD various subsystems, each which made up orbital...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTBinuclear and polymeric gold(I) complexesYuansheng Jiang, Santiago Alvarez, Roald HoffmannCite this: Inorg. Chem. 1985, 24, 5, 749–757Publication Date (Print):February 1, 1985Publication History Published online1 May 2002Published inissue 1 February 1985https://pubs.acs.org/doi/10.1021/ic00199a023https://doi.org/10.1021/ic00199a023research-articleACS PublicationsRequest reuse permissionsArticle Views570Altmetric-Citations178LEARN ABOUT THESE...

An efficient implementation of the “cluster-in-molecule” (CIM) approach is presented for performing local electron correlation calculations in a basis orthogonal occupied and virtual localized molecular orbitals (LMOs). The main idea this that significant excitation amplitudes can be approximately obtained by solving coupled cluster (or Møller-Plesset perturbation theory) equations series “clusters,” each which contains subset LMOs. In present implementation, we have proposed simple...

An electrostatic field-adapted molecular fractionation with conjugated caps (EFA-MFCC) approach is implemented for treating macromolecules several charge centers. The fragmentation performed in an "electrostatic field," which described by putting point charges on centers, directly affecting the Hamiltonians of both fragments and caps. So present method does not need truncation during calculation interactions. Our test calculations a series charged model systems biological using HF B3LYP...

Applying the density matrix renormalization group (DRMG) method to a nonempirical valence bond (VB) model Hamiltonian, we studied polyacene oligomers of different lengths in strong electron correlation limit. Geometrical optimizations were performed for lowest singlet and triplet states up [40]-acene, convergence toward polymer limit is observed interior oligomer. For large oligomers, as well polymer, ground state can be reasonably determined singlet. Furthermore, high similarity between...

The ferroelectricity of BaTiO3 is investigated with the plane-wave pseudopotential method and LCAO quantum chemical approach in framework density functional theory (DFT). Potential energy surfaces various atomic displacements influence lattice strain volume on are examined. On basis potential surfaces, phonon frequencies also computed, which agreement experiment results. obtained show that ferroelectric phase transition (from cubic to tetragonal phase) decisively controlled by Ti...

The geometric and electronic structures of oligothiophene dications (with 6 to 12 monomers) have been revisited using the spin-unrestricted broken symmetry hybrid density functional B3LYP method. It is found that there exists a transition region bipolaron two-polaron structure conversion in moderately sized oligomers, as had reported earlier an AM1-CI calculation. According our calculation, should be from hexamer octamer. TD-DFT simulation led different rationalization experimental...

The geometrical structures and electronic properties of borole/thiophene cooligomers are studied employing the density functional theory with B3LYP functional. borole-containing oligomers have been suggested to quinoid structure distinct biradical character. introduction thiophene rings into oligoborole will retard appearance consequently stabilize oligomers. Electronic structrues polyborole copolymers investigated by periodic boundary condition (PBC) cyclic oligomer model. Both PBC models...

Comparative studies on the four ATiO3 compounds are carried out to investigate different ferroelectric behaviors of basis experimental and theoretically optimized lattice structures. The stability predicted from calculated total energies is in agreement with observation. obtained potential energy surfaces (PESs) show Ti displacements CaTiO3 SrTiO3 result single-well whereas BaTiO3 PbTiO3 they produce double-well potential. In contrast alkaline earth metal atoms, PES Pb displacement double...

Density functional calculations have been performed to explore the sextet, quartet, and doublet potential energy surfaces of methane dehydrogenation by gas-phase Os+ for understanding reaction mechanism. The minimum path is found involve spin inversion three times in different steps. Totally, states (sextet, doublet) are involved whole reaction. Specifically, most likely proceed through following steps: 6Os+ + CH4 → OsCH4+ (61) HOsCH3 (42) HOsH(CH2)+ (23) (H2)Os(CH2)+ (44) Os(CH2)+ (45) H2....

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTrinuclear clusters of early transition metals: Jahn-Teller distortions and electronic structureYuansheng Jiang, Aoqing Tang, Roald Hoffmann, Jinling Huang, Jiaxi LuCite this: Organometallics 1985, 4, 1, 27–34Publication Date (Print):January 1985Publication History Published online1 May 2002Published inissue 1 January 1985https://pubs.acs.org/doi/10.1021/om00120a006https://doi.org/10.1021/om00120a006research-articleACS PublicationsRequest reuse...

Sinus floor elevation (SFE) is a widely established surgical procedure for dental implant placement in the atrophic posterior maxilla. However, presence of maxillary sinus cysts (MSCs) can significantly complicate this intervention. This study presents and evaluates efficacy safety Digitally Guided Aspiration Technique (DGAT), novel approach managing MSCs during SFE procedures. Implant survival success rates were evaluated according to criteria, all complications systematically documented....

The cover image is based on the article Digitally Guided Aspiration Technique for Maxillary Sinus Floor Elevation in Presence of Cysts: A Case Series by Yuhuan Jiang et al., https://doi.org/10.1111/cid.70009 .

The effects of siloles and doping with positive negative charges on the electronic structures band gaps silole/thiophene copolymers are studied employing density functional theory time-dependent B3LYP functional. optimized geometries, calculated excitation energies, extrapolated agree available experimental results. decreasing trend increasing silole content in is good agreement observations. Doping significantly shortens carbon−carbon distances along backbones lowers energies thiophene...

We investigated electronic structures of four sets monomers and polymers comprising phenyl rings five-membered hetero(aromatic) moieties connected with double-bond -X=X- linkages (X = CH, SiH, GeH, N, P, As) by density functional theory, time-dependent periodic boundary condition calculations B3LYP functional. Electronic poly(p-phenylenevinylene) (PPV) analogues are primarily dominated central moieties. The introduction ethylene homologues group 14 15 elements was demonstrated to be a...

Solvent effects on electronic structures and chain conformations of α-oligothiophenes nTs (n = 1 to 10) are investigated in solvents n-hexane, 1,4-dioxane, carbon tetrachloride, chloroform, water by using density functional theory (DFT) molecular dynamics (MD) simulations. Both implicit explicit solvent models employed. The polarized continuum model (PCM) calculations MD simulations demonstrate the weak α-oligothiophenes. lowest dipole-allowed vertical excitation energies nTs, obtained from...

Unrestricted density functional calculations with spin-projection procedures have been performed for a series of m-phenylene-bridged diradicals to investigate the effects substitution on singlet−triplet (S−T) energy gaps and ground-state multiplicities. Our show that introduction electron-donating (or electron-withdrawing) substituents 4,6-positions m-phenylene moiety or radical centers, both positions, generally leads triplet ground state, although S−T are smaller than parent m-xylylene...

The spatial orbital formulations of block correlated coupled cluster (BCCC) theory with a general CASSCF reference function (CAS-BCCC in short) is derived and an efficient implementation this approach at the four-block correlation level (abbreviated CAS-BCCC4) reported. We have applied CAS-BCCC4 to investigate energy barriers for several reactions (the ring-opening isomerization cyclopropyl radical, cyclobutene, cyclobutadiene, bicyclo[3.1.0]hex-2-ene), spectroscopic constants multibond...

Abstract The genesis and influencing factors of the colour chrysoprase were studied based on results transmission electron microscopy X-ray fluorescence, ultraviolet–visible Raman spectroscopies. show that under a 6504-K fluorescent lamp, is divided into grades fancy, fancy intense deep. lightness affected mainly by its chromium content, chroma nickel content hue angle sum ferrum contents. related significantly to window occurs between two main bands centred at 380 660 nm absorption peaks in...

Chrysoprase is a popular gemstone with consumers because of its charming apple green colour but scientific classification has not yet been achieved. In this research, we determined the most effective background Munsell Chart for chrysoprase grading under 6504K fluorescent lamp and applied an affinity propagation (AP) clustering algorithm to coloured gems first time. Forty gem-quality samples from Australia were studied using UV-VIS spectrophotometer neutral grey backgrounds. The results...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTBond Lengths, Reactivities, and Aromaticities of Benzenoid Hydrocarbons Based on Valence Bond CalculationsShuhua Li Yuansheng JiangCite this: J. Am. Chem. Soc. 1995, 117, 32, 8401–8406Publication Date (Print):August 1, 1995Publication History Published online1 May 2002Published inissue 1 August 1995https://pubs.acs.org/doi/10.1021/ja00137a013https://doi.org/10.1021/ja00137a013research-articleACS PublicationsRequest reuse permissionsArticle...

Quantum chemistry and molecular mechanics calculations are performed to study formation mechanisms packing structures of octadecanal octadecene monolayers on Si(111). The radical chain mechanism is investigated by density functional theory with cluster models. Transition states key steps involving abstracting a neighboring hydrogen atom from the surface confirmed six-membered ring structures. Energy barriers for abstractions H form new reactive Si radicals in substitution Si(111) via Si−O...