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Journal ArticleDOI

Equation of motion coupled cluster methods for electron attachment and ionization potential in polyacenes

TL;DR: In this paper, the authors employed the EA/IP equation of motion coupled cluster singles and doubles (EA/IP-EOMCCSD) method for linear polyacenes and their electron affinity (EA) and ionization potential (IP) properties.
About: This article is published in Chemical Physics Letters.The article was published on 2015-11-16 and is currently open access. It has received 12 citations till now. The article focuses on the topics: Hexacene & Coupled cluster.
Citations
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Journal ArticleDOI
TL;DR: The unusual intrinsic electronic structure of the [B12X12]2- MCAs provides the basis for a molecular level understanding of their observed unique physical and chemical properties and a new paradigm for understanding the properties of these MCAs with not well-separated charges that departs from the prevailing model used for spatially separated charges.
Abstract: The stability and electron loss process of numerous multiply charged anions (MCAs) have been traditionally explained in terms of the classical Coulomb interaction between spatially separated charged groups. An understanding of these processes in MCAs with not well-separated excess charges is still lacking. We report the surprising properties and physical behavior of [B12X12]2–, X = F, Cl, Br, I, At, which are MCAs with not well-separated excess charges and cannot be described by the prevailing classical picture. In this series of MCAs, comprising a “boron core” surrounded by a “halogen shell”, the sign of the total charge in these two regions changes along the halogen series from X = F–At. With the aid of experimental photoelectron spectroscopy and highly correlated ab initio electronic structure calculations, we demonstrate that the trend in the electronic stability of these MCAs is determined by the interplay between the Coulomb (de)stabilization originating from the “boron core” and “halogen shell” and...

51 citations

Journal ArticleDOI
TL;DR: A key aspect of this work is the determination of the frequency dependent self-energy, Σ(ω), which reveals a diagonally dominate block structure where as the non-local correlation increases, the block size increases proportionally.
Abstract: In this paper, we report on the development of a parallel implementation of the coupled-cluster (CC) Green function formulation (GFCC) employing single and double excitations in the cluster operator (GFCCSD). A key aspect of this work is the determination of the frequency dependent self-energy, Σ(ω). The detailed description of the underlying algorithm is provided, including approximations used that preserve the pole structure of the full GFCCSD method, thereby reducing the computational costs while maintaining an accurate character of methodology. Furthermore, for systems with strong local correlation, our formulation reveals a diagonally dominate block structure where as the non-local correlation increases, the block size increases proportionally. To demonstrate the accuracy of our approach, several examples including calculations of ionization potentials for benchmark systems are presented and compared against experiment.

46 citations

Journal ArticleDOI
20 Jun 2016-ACS Nano
TL;DR: The morphological evolution of poly(3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester blends that are commensurate with the size of a BHJ thin film is examined and nanoscale geometries of the P3HT oligomers, LUMO and HOMO energy levels calculated by density functional theory are found to be invariant across the donor/acceptor interface.
Abstract: Understanding how additives interact and segregate within bulk heterojunction (BHJ) thin films is critical for exercising control over structure at multiple length scales and delivering improvements in photovoltaic performance. The morphological evolution of poly(3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) blends that are commensurate with the size of a BHJ thin film is examined using petascale coarse-grained molecular dynamics simulations. Comparisons between two-component and three-component systems containing short P3HT chains as additives undergoing thermal annealing demonstrate that the short chains alter the morphology in apparently useful ways: they efficiently migrate to the P3HT/PCBM interface, increasing the P3HT domain size and interfacial area. Simulation results agree with depth profiles determined from neutron reflectometry measurements that reveal PCBM enrichment near substrate and air interfaces but a decrease in that PCBM enrichment when a small amount of shor...

28 citations

Journal ArticleDOI
TL;DR: It is demonstrated that the electronegativity of C20nH20 systems remains, to a large extent, independent of the nanotube length.
Abstract: In this paper, we apply equation-of-motion coupled cluster (EOM-CC) methods in the studies of the vertical ionization potentials (IPs) and electron affinities (EAs) for a series of single-walled carbon nanotubes (SWCNT). The EOM-CC formulations for IPs and EAs employing excitation manifolds spanned by single and double excitations (IP/EA-EOM-CCSD) are used to study the IPs and EAs of the SWCNTs as a function of the nanotube length. Several armchair nanotubes corresponding to C20nH20 models with n = 2–6 have been used in benchmark calculations. In agreement with previous studies, we demonstrate that the electronegativity of C20nH20 systems remains, to a large extent, independent of the nanotube length. We also compare IP/EA-EOM-CCSD results with those obtained with coupled cluster models with single and double excitations corrected by perturbative triples, CCSD(T), and density functional theory (DFT) using global and range-separated hybrid exchange–correlation functionals.

9 citations

Journal ArticleDOI
TL;DR: In this article , a subspace projection scheme was proposed to evaluate resonance positions and widths at the overall cost of a single electronic structure calculation for the complex absorbing potential equation-of-motion coupled-cluster (CAP-EOM-CC) method.
Abstract: The complex absorbing potential equation-of-motion coupled-cluster (CAP-EOM-CC) method is routinely used to investigate metastable electronic states in small molecules. However, the requirement of evaluating eigenvalue trajectories presents a barrier to larger simulations, as each point corresponding to a different value of the CAP strength parameter requires a unique eigenvalue calculation. Here, we present a new implementation of CAP-EOM-CCSD that uses a subspace projection scheme to evaluate resonance positions and widths at the overall cost of a single electronic structure calculation. We analyze the performance of the projected CAP-EOM-CC scheme against the conventional scheme, where the CAP is incorporated starting from the Hartree-Fock level, for various small and medium sized molecules, and investigate its sensitivity to various parameters. Finally, we report resonance parameters for a set of molecules commonly used for benchmarking CAP-based methods, and we report estimates of resonance energies and widths for 1- and 2-cyanonaphtalene, molecules that were recently detected in the interstellar medium.

7 citations

References
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Journal ArticleDOI
TL;DR: In this paper, the authors extended the full triples equation-of-motion (EOM) coupled cluster (CC) method to electron attached states and achieved a scaling no higher than nocc2nvir5.
Abstract: We extend the full triples equation-of-motion (EOM) coupled cluster (CC) method to electron attached states. Proper factorization of the three- and four-body parts of the effective Hamiltonian makes it possible to achieve for the EA-EOM part a scaling no higher than nocc2nvir5. The method is calibrated by the evaluation of the valence vertical electron affinities for the C2 and O3 molecules for several basis sets up to 160 basis functions. For C2, EA-EOM-CCSDT gives 3.24 eV at the extrapolated basis limit, while the experimental adiabatic EA is equal to 3.27±0.008 eV. For O3 the agreement is ∼1.9 eV compared to an adiabatic value of 2.1 eV.

137 citations

Journal ArticleDOI
TL;DR: In this paper, a method for determining adiabatic electron affinities from reduction potentials, and vice versa, was established for a series of fullerenes, aromatic hydrocarbons, metalloporphyrins and metal complexes in dimethylformamide (DMF).
Abstract: Differences in energy for neutral molecule and negative ions upon going from the gas phase to solution. - {delta}{delta}G{sub sol}, have been calculated from gas phase electron affinites and half-wave reduction potentials for a series of fullerenes, aromatic hydrocarbons, metalloporphyrins, and metal complexes in dimethylformamide (DMF). For those compounds with similar charge delocalization, the value of -{delta}{delta}G{sub sol} is constant and equal to 1.76 {+-} 0.06 eV for the fullerenes, 1.99 {+-} 0.05 eV for the aromatic hydrocarbons and the metalloporphyrins, and 2.19 {+-} 0.14 eV for the metal acetylacetonates. The fullerenes form a new class of molecules in which the charge is highly delocalized, and this is demonstrated by the relatively low value of -{Delta}{Delta}{sub sol}. A procedure for determining adiabatic electron affinities from reduction potentials, and vice versa, is established. This procedure is applied to benzene to give an electron affinity of {minus}0.7 {+-} 0.14 eV, to La @ C{sub 82} to give an electron affinity of 3.21 {+-} 0.06 eV, and to Y @ C{sub 82} to give an electron affinity of 3.32 {+-} 0.06 eV. On the other hand, a value of E{sub 1/2} = 0.09 {+-} 0.14 V vs SCE is predicted for the reductionmore » of Ca@C{sub 60} in DMF based upon a reported electron affinity of 3.0 {+-} 0.1 eV. 36 refs., 4 figs., 3 tabs.« less

130 citations

Journal ArticleDOI
TL;DR: The use of surface-initiated ring-opening metathesis polymerization (SI- ROMP) for producing polymer dielectric layers is reported, demonstrating for the first time that SI-ROMP can be used in the construction of organic thin-film electronic devices.
Abstract: The use of surface-initiated ring-opening metathesis polymerization (SI-ROMP) for producing polymer dielectric layers is reported. Surface tethering of the catalyst to Au or Si/SiO2 surfaces is accomplished via self-assembled monolayers of thiols or silanes containing reactive olefins. Subsequent SI-ROMP of norbornene can be conducted under mild conditions. Pentacene semiconducting layers and gold drain/source electrodes are deposited over these polymer dielectric films. The resulting field effect transistors display promising device characteristics, demonstrating for the first time that SI-ROMP can be used in the construction of organic thin-film electronic devices.

130 citations

Journal ArticleDOI
TL;DR: In this paper, the EOMCCSDt method with singles, doubles, and a selected set of triples defined through active orbitals is applied to the excited-state potential energy curves of the CH+ ion.

115 citations

Journal ArticleDOI
TL;DR: In this article, the generalized moments of the EOMCC equations were extended to excited states via the equation-of-motion coupled-cluster (EOMCC) formalism.
Abstract: The recently proposed method of moments of coupled-cluster equations (MMCC) is extended to excited states via the equation-of-motion coupled-cluster (EOMCC) formalism. The main idea of the new MMCC theory is that of the noniterative energy corrections which, when added to the excited-state energies obtained in standard approximate EOMCC calculations, recover the exact energies. The MMCC corrections are expressed in terms of the generalized moments of the EOMCC equations. Approximate variants of the excited-state MMCC formalism, including the MMCC(2,3) approach, are introduced. In the MMCC(2,3) method, very simple energy corrections, expressed in terms of matrix elements of the triples-reference, triples-singles, and triples-doubles blocks of the EOMCCSD (EOMCC singles and doubles) similarity-transformed Hamiltonian, are added to the excited-state energies obtained in EOMCCSD calculations. The performance of the MMCC(2,3) approach is illustrated by the results of pilot calculations for the potential energy...

108 citations