Publications

Higher-order van der Waals coefficients from static multipole polarizability

Phase-Selective Cation-Exchange Chemistry in Sulfide Nanowire Systems

As a cation-deficient, p-type semiconductor, copper sulfide (Cu(2-x)S) shows promise for applications such as photovoltaics, memristors, and plasmonics. However, these applications demand precise tuning of the crystal phase as well as the stoichiometry of Cu(2-x)S, an ongoing challenge in the synthesis of Cu(2-x)S materials for a specific application. Here, a detailed transformation diagram of cation-exchange (CE) chemistry from cadmium sulfide (CdS) into Cu(2-x)S nanowires (NWs) is reported. By varying the reaction time and the reactants' concentration ratio, the progression of the CE process was captured, and tunable crystal phases of the Cu(2-x)S were achieved. It is proposed that the evolution of Cu(2-x)S phases in a NW system is dependent on both kinetic and thermodynamic factors. The reported data demonstrate that CE can be used to precisely control the structure, composition, and crystal phases of NWs, and such control may be generalized to other material systems for a variety of practical applications.

The electron localization function and the chemical interpretation of Fermi orbital descriptors in Fermi–Löwdin self-interaction correction calculations

A set of Fermi orbital descriptors (FODs), representing "semi-classical" electronic positions, is a crucial ingredient in the Fermi-Löwdin orbital self-interaction correction (FLOSIC) method. The FODs are utilized to generate Fermi orbitals, which, in turn, are symmetrically orthogonalized to give the Fermi-Löwdin orbitals employed in FLOSIC calculations. It has been argued, based on empirical evidence, that FODs carry chemical bonding information and that FOD arrangements are reminiscent of electron distributions predicted by Lewis or Linnett theory. Here, we show that there is a formal connection between FODs and critical points of the electron localization function (ELF) and illustrate this fact for several cases where fully relaxed FODs from FLOSIC calculations closely resemble the structure of critical points (CPs). We also propose a new localization function, the SIC-ELF, based on the local mobility of the Fermi orbitals. In certain instances involving double and triple bonds, FLOSIC FODs offer a more precise interpretation of the chemical bonding structure suggested by Lewis theory than ELF or SIC-ELF. We suggest that the connection between FODs and CPs can be exploited to obtain initial FOD configurations for FLOSIC calculations.

Relevance of the Slowly Varying Electron Gas to Atoms, Molecules, and Solids

We present a Thomas-Fermi-inspired density scaling under which electron densities of atomic, molecular, or condensed matter become both large and slowly varying, so that semiclassical approximations and second-order density gradient expansions are asymptotically exact for the kinetic and exchange energies. Thus, even for atoms and molecules, density-functional approximations should recover the universal second-order gradient expansions in this limit. We also explain why common generalized gradient approximations for exchange do not.

Perdew-Zunger self-interaction correction: How wrong for uniform densities and large-<i>Z</i> atoms?

Semilocal density functionals for the exchange-correlation energy of a many-electron system cannot be exact for all one-electron densities. In 1981, Perdew and Zunger (PZ) subtracted the fully nonlocal self-interaction error orbital-by-orbital, making the corrected functional exact for all collections of separated one-electron densities and making no correction to the exact functional. Although the PZ self-interaction correction (SIC) eliminates many errors of semilocal functionals, it is often worse for equilibrium properties of sp-bonded molecules and solids. Nonempirical semilocal functionals are usually designed to be exact for electron gases of uniform density and, thus, also make 0% error for neutral atoms in the limit of large atomic number Z, but PZ SIC is not so designed. For localized SIC orbitals, we show analytically that the local spin density approximation (LSDA)-SIC correlation energy per electron of the uniform gas in the high-density limit makes an error of -50% in the spin-unpolarized case and -100% in the fully spin-polarized case. Then we extrapolate from the Ne, Ar, Kr, and Xe atoms to estimate the relative errors of the PZ SIC exchange-correlation energies (with localized SIC orbitals) in the limit of large atomic number: about +5.5% for the LSDA-SIC and about -3.5% for nonempirical generalized gradient [Perdew-Burke-Ernzerhof (PBE)-SIC] and meta-generalized gradient strongly constrained and appropriately normed (SCAN)-SIC approximations. The SIC errors are considerably larger than those that have been estimated for LSDA-SIC by approximating the localized SIC orbitals for the uniform gas and may explain the errors of PZ SIC for equilibrium properties, opening the door to a generalized SIC that is more widely accurate.

DFT study of bulk SiO_2: Pressure-induced phase transition from α-quartz to stishovite

Accurate and easy method for work function calculations

Simulation of All-Order Density-Functional Perturbation Theory, Using the Second Order and the Strong-Correlation Limit

To boost the accuracy of electronic structure calculations, the exchange-correlation energy may be constructed from the Kohn-Sham orbitals. A formally exact construction is the density-functional perturbation series, which appears to diverge for many real systems. We predict the radius of convergence and resum this series, using only exact exchange and second-order correlation plus explicit density functionals for the strong-interaction limit. Our new correlation functional, along with exact exchange, predicts atomization energies with competitive accuracy and without the usual error cancellation.

Density functionals for the strong-interaction limit

The strong-interaction limit of density-functional (DF) theory is simple and provides information required for an accurate resummation of DF perturbation theory. Here we derive the point-charge-plus-continuum (PC) model for that limit, and its gradient expansion. The exchange-correlation (xc) energy ${E}_{\mathrm{xc}}[\ensuremath{\rho}]\ensuremath{\equiv}{\ensuremath{\int}}_{0}^{1}d\ensuremath{\alpha}{W}_{\ensuremath{\alpha}}[\ensuremath{\rho}]$ follows from the xc potential energies ${W}_{\ensuremath{\alpha}}$ at different interaction strengths $\ensuremath{\alpha}&gt;~0$ [but at fixed density $\ensuremath{\rho}(\mathbf{r})].$ For small $\ensuremath{\alpha}\ensuremath{\approx}0,$ the integrand ${W}_{\ensuremath{\alpha}}$ is obtained accurately from perturbation theory, but the perturbation expansion requires resummation for moderate and large $\ensuremath{\alpha}.$ For that purpose, we present density functionals for the coefficients in the asymptotic expansion ${W}_{\ensuremath{\alpha}}\ensuremath{\rightarrow}{W}_{\ensuremath{\infty}}{+W}_{\ensuremath{\infty}}^{\ensuremath{'}}{\ensuremath{\alpha}}^{\ensuremath{-}1/2}$ for $\stackrel{\ensuremath{\rightarrow}}{\ensuremath{\alpha}}\ensuremath{\infty}$ in the PC model. ${W}_{\ensuremath{\infty}}^{\mathrm{PC}}$ arises from strict correlation, and ${W}_{\ensuremath{\infty}}^{\ensuremath{'}\mathrm{PC}}$ from zero-point vibration of the electrons around their strictly correlated distributions. The PC values for ${W}_{\ensuremath{\infty}}$ and ${W}_{\ensuremath{\infty}}^{\ensuremath{'}}$ agree with those from a self-correlation-free meta-generalized gradient approximation, both for atoms and for atomization energies of molecules. We also (i) explain the difference between the PC cell and the exchange-correlation hole, (ii) present a density-functional measure of correlation strength, (iii) describe the electron localization and spin polarization energy in a highly stretched ${\mathrm{H}}_{2}$ molecule, and (iv) discuss the soft-plasmon instability of the low-density uniform electron gas.

The new observation of C18O (J=1-0) molecular emission in W31

Compression of Metallic Clusters in the Stabilized Jellium Model

Both 2-lysophosphatidylcholine and cis-unsaturated fatty acids were previously shown to intensify agonist-induced cellular responses by enhancing the diacylglycerol-dependent activation of protein kinase C. Consistent with these observations, extracellular, secretory group II phospholipase A2, when added directly to human resting T lymphocytes, greatly potentiates their activation that was induced by a membrane-permeant diacylglycerol and ionomycin, as determined by the expression of the alpha subunit of the interleukin 2 receptor and thymidine incorporation into DNA. Diacylglycerol and ionomycin were essential for this cellular response, and phospholipase A2 alone showed no effect. The amount of 2-lysophosphatidylcholine produced in these cells by the exogenous phospholipase A2 was greatly increased in the presence of diacylglycerol and ionomycin, suggesting that the membrane phospholipids became susceptible to the phospholipase A2 when protein kinase C was activated. The results suggest that phospholipase A2 secreted into inflammatory sites plays a role in the propagation of cellular responses. Protein kinase C may function in the hydrolysis of membrane phospholipids by the exogenous phospholipase A2, and the products of this phospholipid hydrolysis enhance agonist-induced protein kinase C activation, thereby intensifying cellular responses.

Ab Initio Calculation of Coupling-Constant Averaged Exchange–Correlation Holes for Spherically Symmetric Atoms

Accurate approximation of the exchange-correlation (XC) energy in density functional theory (DFT) calculations is essential for reliably modeling electronic systems. Many such approximations are developed from models of the XC hole; accurate reference XC holes for real electronic systems are crucial for evaluating the accuracy of these models however the availability of reliable reference data is limited to a few systems. In this study, we employ the Lieb optimization with a coupled cluster singles and doubles (CCSD) reference to construct accurate coupling-constant averaged XC holes, resolved into individual exchange and correlation components, for five spherically symmetric atoms: He, Li, Be, N, and Ne. Alongside providing a new set of reference data for the construction and evaluation of model XC holes, we compare our data against the exchange and correlation hole models of the established local density approximation (LDA) and Perdew-Burke-Ernzerhof (PBE) density functional approximations. Our analysis confirms the established rationalization for the limitations of LDA and the improvement observed with PBE in terms of the hole depth and its long-range decay, which is demonstrated in real-space for this series of spherically symmetric atoms.

Density-functional correction of random-phase-approximation correlation with results for jellium surface energies

Since long-range electron-electron correlation is treated properly in the random phase approximation (RPA), we define short-range correlation as the correction to the RPA. The effects of short-range correlation are investigated here in the local spin density (LSD) approximation and the generalized gradient approximation (GGA). Results are presented for atoms, molecules, and jellium surfaces. It is found that (1) short-range correlation energies are less sensitive to the inclusion of density gradients than are full correlation energies, and (2) short-range correlation makes a surprisingly small contribution to surface and molecular atomization energies. In order to improve the accuracy of electronic-structure calculations, we therefore combine a GGA treatment of short-range correlation with a full RPA treatment of the exchange-correlation energy. This approach leads to jellium surface energies close to those of the LSD approximation for exchange and correlation together (but not for each separately).

New Meta-Generalized Gradient Approximation for Exchange and Correlation

Correction to “Layered Semiconductor Cr_0.32Ga_0.68Te_2.33 with Concurrent Broken Inversion Symmetry and Ferromagnetism: A Bulk Ferrovalley Material Candidate”

ADVERTISEMENT RETURN TO ISSUEPREVAddition/CorrectionNEXTORIGINAL ARTICLEThis notice is a correctionCorrection to "Layered Semiconductor Cr0.32Ga0.68Te2.33 with Concurrent Broken Inversion Symmetry and Ferromagnetism: A Bulk Ferrovalley Material Candidate"Yingdong GuanYingdong GuanMore by Yingdong Guanhttps://orcid.org/0000-0002-1357-6258, Leixin MiaoLeixin MiaoMore by Leixin Miao, Jingyang HeJingyang HeMore by Jingyang Hehttps://orcid.org/0000-0002-3886-3659, Jinliang NingJinliang NingMore by Jinliang Ning, Yangyang ChenYangyang ChenMore by Yangyang Chen, Weiwei XieWeiwei XieMore by Weiwei Xie, Jianwei SunJianwei SunMore by Jianwei Sunhttps://orcid.org/0000-0002-2361-6823, Venkatraman GopalanVenkatraman GopalanMore by Venkatraman Gopalan, Jun ZhuJun ZhuMore by Jun Zhuhttps://orcid.org/0000-0001-8100-967X, Xiaoping WangXiaoping WangMore by Xiaoping Wanghttps://orcid.org/0000-0001-7143-8112, Nasim Alem*Nasim AlemMore by Nasim Alemhttps://orcid.org/0000-0003-0009-349X, Qiang Zhang*Qiang ZhangMore by Qiang Zhanghttps://orcid.org/0000-0003-0389-7039, and Zhiqiang Mao*Zhiqiang MaoMore by Zhiqiang Maohttps://orcid.org/0000-0002-4920-3293Cite this: J. Am. Chem. Soc. 2023, 145, 39, 21696Publication Date (Web):September 21, 2023Publication History Received30 August 2023Published online21 September 2023Published inissue 4 October 2023https://pubs.acs.org/doi/10.1021/jacs.3c09488https://doi.org/10.1021/jacs.3c09488correctionACS PublicationsCopyright © 2023 American Chemical Society. This publication is available under these Terms of Use. Request reuse permissions This publication is free to access through this site. Learn MoreArticle Views681Altmetric-Citations-LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail PDF (761 KB) Get e-Alertsclose Get e-Alerts