Locating Multiple Self-Consistent Field Solutions: An Approach Inspired by Metadynamics

Thom, Alex J. W.; Head‐Gordon, Martin

doi:10.1103/physrevlett.101.193001

Cited by 83 publications

(123 citation statements)

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“…In addition, we note that the NO + -Ar surface employed in that work 23 has the Ar on the wrong side of the NO moiety, and this must be borne in mind when considering those results. For example, the conclusions therein regarding theÃ ←X spectrum for NO-Ar do not agree with our recent work, 14 [24][25][26][27][28][29] The stimuli for the present work were thus two-fold. First, to investigate the accuracy of excited state PESs computed using second order Møller-Plesset perturbation theory applied to an excited state HF reference wavefunction for states higher in energy than theÃ state, and second to test the published assignments of theC state spectra.…”

Section: Introductioncontrasting

confidence: 87%

Interaction of the NO 3pπ Rydberg state with Ar: Potential energy surfaces and spectroscopy

Ershova

Kłos

Harris

et al. 2013

The Journal of Chemical Physics

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We present the experimental and simulated (2+1) REMPI spectrum of the $\tilde C\,^2 \Pi$C̃Π2 state of the NO–Ar complex, in the vicinity of the 3p Rydberg state of NO. Two Rydberg states of NO are expected in this energy region: the C2Π (3pπ) and D2Σ+ (3pσ) states, and we concentrate on the former here. When the C2Π (3pπ) state interacts with Ar at nonlinear orientations, the symmetry is lowered to Cs, splitting the degeneracy of the 2Π state to yield $\tilde C$C̃(2A″) and $\tilde C$C̃(2A′) states. For these two states of NO–Ar, we calculate potential energy surfaces using second order Møller-Plesset perturbation theory, exploiting a procedure to converge the reference Hartree-Fock wavefunction to describe the excited states, the maximum overlap method. The bound rovibrational states obtained from the surfaces are used to simulate the electronic spectrum, which is in excellent agreement with experiment, providing assignments for the observed spectral lines from the calculated rovibrational wavefunctions.

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Section: Introductioncontrasting

confidence: 87%

Interaction of the NO 3pπ Rydberg state with Ar: Potential energy surfaces and spectroscopy

Ershova

Kłos

Harris

et al. 2013

The Journal of Chemical Physics

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“…Metadynamics and non-orthogonal configuration interaction (NOCI): SCF metadynamics [138] allows one to find alternative minima within the SCF framework (either HF or KS-DFT). Alternative minima are obtained by applying a bias in density matrix space at the locations of previously found minima and using standard convergence algorithms on this modified potential energy surface.…”

Section: Algorithm Developmentsmentioning

confidence: 99%

Advances in molecular quantum chemistry contained in the Q-Chem 4 program package

Shao¹,

Gan²,

Epifanovsky³

et al. 2014

Molecular Physics

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A summary of the technical advances that are incorporated in the fourth major release of the Q-Chem quantum chemistry program is provided, covering approximately the last seven years. These include developments in density functional theory methods and algorithms, nuclear magnetic resonance (NMR) property evaluation, coupled cluster and perturbation theories, methods for electronically excited and openshell species, tools for treating extended environments, algorithms for walking on potential surfaces, analysis tools, energy and electron transfer modelling, parallel computing capabilities, and graphical user interfaces. In addition, a selection of example case studies that illustrate these capabilities is given. These include extensive benchmarks of the comparative accuracy of modern density functionals for bonded and non-bonded interactions, tests of attenuated second order Møller-Plesset (MP2) methods for intermolecular interactions, a variety of parallel performance benchmarks, and tests of the accuracy of implicit solvation models. Some specific chemical examples include calculations on the strongly correlated Cr 2 dimer, exploring zeolitecatalysed ethane dehydrogenation, energy decomposition analysis of a charged ter-molecular complex arising from glycerol photoionisation, and natural transition orbitals for a Frenkel exciton state in a nine-unit model of a self-assembling nanotube.Keywords quantum chemistry, software, electronic structure theory, density functional theory, electron correlation, computational modelling, Q-Chem Disciplines Chemistry CommentsThis article is from Molecular Physics: An International Journal at the Interface Between Chemistry and Physics 113 (2015): 184, doi:10.1080/00268976.2014. RightsWorks produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted. Authors 185A summary of the technical advances that are incorporated in the fourth major release of the Q-CHEM quantum chemistry program is provided, covering approximately the last seven years. These include developments in density functional theory methods and algorithms, nuclear magnetic resonance (NMR) property evaluation, coupled cluster and perturbation theories, methods for electronically excited and open-shell species, tools for treating extended environments, algorithms for walking on potential surfaces, analysis tools, energy and electron transfer modelling, parallel computing capabilities, and graphical user interfaces. In addition, a selection of example case studies that illustrate these capabilities is given. These include extensive benchmarks of the comparative accuracy of modern density functionals for bonded and non-bonded interactions, tests of attenuated second order Møller-Plesset (MP2) methods for intermolecular interactions, a variety of parallel performance benchmarks, and tests of the accuracy of implicit solvation models. Some specific chemical examples include calculations on the strongly corre...

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“…For HF (Ref. 16) and local-density approximation (LDA)/generalized gradient approximation + U (GGA + U ) (Ref. 17) calculations, it is well known that the self-consistency cycle can reach many local minima instead of the global minimum.…”

mentioning

confidence: 99%

Unified description of ground and excited states of finite systems: The self-consistentGWapproach

et al. 2012

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GW calculations with a fully self-consistent Green's function G and screened interaction W -based on the iterative solution of the Dyson equation-provide a consistent framework for the description of groundand excited-state properties of interacting many-body systems. We show that for closed-shell systems selfconsistent GW reaches the same final Green's function regardless of the initial reference state. Self-consistency systematically improves ionization energies and total energies of closed-shell systems compared to G 0 W 0 based on Hartree-Fock and (semi)local density-functional theory. These improvements also translate to the electron density, as exemplified by an improved description of dipole moments, and permit us to assess the quality of ground-state properties such as bond lengths and vibrational frequencies. Many-body perturbation theory (MBPT) 1 in the GW approximation of the electronic self-energy 2,3 is presently the state-of-the-art method for describing the spectral properties of solids. 4,5 Recently, it has steadily gained popularity for molecules and nanosystems. 6 In addition, MBPT provides a prescription to extract total energies and structural properties from the GW approximation and therefore is a consistent theoretical framework for single-particle spectra and total energies.Due to its numerical cost and algorithmic difficulties, the GW method has only recently been applied self-consistently (i.e., nonperturbatively) to atoms, 7 molecules, 8 and molecular transport. 6 Predominantly, GW calculations are still performed perturbatively (one-shot G 0 W 0 ) on a set of singleparticle orbitals and eigenvalues obtained from a preceding density-functional theory 9 (DFT) or Hartree-Fock (HF) calculation. This procedure introduces a considerable starting-point dependence, 10-12 which can be eliminated by iterating the Dyson equation to self-consistency. [6][7][8]13 The resulting selfconsistent GW (sc-GW ) framework is a conserving approximation in the sense of Baym and Kadanoff 14 (i.e., it satisfies momentum, energy, and particle number conservation laws). sc-GW gives total energies 15 free from the ambiguities of the G 0 W 0 scheme, in which the results depend on the chosen total energy functional. 7 However, as in any self-consistent theory, the question remains if the self-consistent solution of the Dyson equation is unique. This issue is fundamentally different from the initial-state dependence of G 0 W 0 . For HF (Ref. 16) and local-density approximation (LDA)/generalized gradient approximation + U (GGA + U ) (Ref. 17) calculations, it is well known that the self-consistency cycle can reach many local minima instead of the global minimum. Moreover, a previous sc-GW study for the Be atom showed that normconserving pseudopotential calculations do not produce the same final GW Green's function (and the corresponding ionization potential) as all-electron calculations. 18 In this Rapid Communication, we demonstrate certain key aspects of the sc-GW approximation for closed-shell molecules that make...

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Locating Multiple Self-Consistent Field Solutions: An Approach Inspired by Metadynamics

Cited by 83 publications

References 21 publications

Interaction of the NO 3pπ Rydberg state with Ar: Potential energy surfaces and spectroscopy

Interaction of the NO 3pπ Rydberg state with Ar: Potential energy surfaces and spectroscopy

Advances in molecular quantum chemistry contained in the Q-Chem 4 program package

Unified description of ground and excited states of finite systems: The self-consistentGWapproach

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