Evidence of instantaneous electron correlation from Compton profiles of crystalline silicon

Pisani, Cesare; Itou, M.; Sakurai, Y.; Yamaki, Ryutaro; Ito, Masahisa; Erba, Alessandro; Maschio, Lorenzo

doi:10.1039/c0cp01604g

Cited by 27 publications

(46 citation statements)

References 20 publications

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“…The KS density matrix therefore has not much to do with the density matrix of the real system, and KS DFT cannot be expected to provide a reasonable description of the momentum density matrix and its derived properties like the directional Compton profile. [45][46][47][48][49] The topic of calculating the density matrix and related quantities using the CRYSCOR code is covered in Section V.…”

Section: Marco Lorenzmentioning

confidence: 99%

“…In particular, the availability of correlated momentum-space properties is of relevance, since KS-DFT cannot provide a reliable description of such quantities. [45][46][47][48]97 As an example of this feature of CRYSCOR, we discuss here two complementary aspects of the DM of a-quartz as reflected in its EMD and its ECD, and the effect of electron correlation on these. All the computational parameters used in these calculations are identical to those of ref.…”

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confidence: 99%

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Cryscor: a program for the post-Hartree–Fock treatment of periodic systems

Pisani

Schütz

Casassa

et al. 2012

Phys. Chem. Chem. Phys.

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CRYSCOR is a periodic post-Hartree-Fock program based on local functions in direct space, i.e., Wannier functions and projected atomic orbitals. It uses atom centered Gaussians as basis functions. The Hartree-Fock reference, as well as symmetry information, is provided by the CRYSTAL program. CRYSCOR presently features an efficient and parallel implementation of periodic local second order Møller-Plesset perturbation theory (MP2), which allows us to study 1D-, 2D-and 3D-periodic systems beyond 1000 basis functions per unit cell. Apart from the correlation energy also the MP2 density matrix, and from that the Compton profile, are available. Very recently, a new module for calculating excitonic band gaps at the uncorrelated Configuration-Interaction-Singles (CIS) level has been added. Other advancements include new extrapolation techniques for calculating surface adsorption on semiinfinite solids. In this paper the diverse features and recent advances of the present CRYSCOR version are illustrated by exemplary applications to various systems: the adsorption of an argon monolayer on the MgO (100) surface, the rolling energy of a boron nitride nanoscroll, the relative stability of different aluminosilicates, the inclusion energy of methane in methane-ice-clathrates, and the effect of electron correlation on charge and momentum density of a-quartz. Furthermore, we present some first tentative CIS results for excitonic band gaps of simple 3D-crystals, and their dependence on the diffuseness of the basis set.

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Section: Marco Lorenzmentioning

confidence: 99%

mentioning

confidence: 99%

Cryscor: a program for the post-Hartree–Fock treatment of periodic systems

Pisani

Schütz

Casassa

et al. 2012

Phys. Chem. Chem. Phys.

Self Cite

127

200

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“…On the other hand, we are now in a position to calculate EMDs of crystalline systems using not only a variety of one-electron approximations, but also a post-HF technique that includes explicitly the Coulomb instantaneous correlation between electrons. A preliminary report on this subject has recently been published; 18 we provide here a more complete account of the experimental results and of the theoretical schemes adopted.…”

Section: Introductionmentioning

confidence: 99%

Pressure-induced transitions in solid nitrogen: Role of dispersive interactions

et al. 2011

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Availability: This is the author's manuscriptCompton profiles of crystalline silicon with a high statistical accuracy and high-resolution (0.11 a.u. in full width at half-maximum) are measured along the three main crystallographic directions and are compared to the predictions of ab initio simulations performed at different levels of theory, within and beyond one-electron approximations. The analysis of the Fourier transform of the Compton profiles reveals the failure of the density matrix extracted from single-determinantal models in reproducing some fine features of the electron momentum density of crystalline materials that can be attributed to the instantaneous Coulomb correlation of the electronic motions. The use of a post-Hartree-Fock periodic scheme allows such features to be satisfactorily reproduced.

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“…In this respect, high-resolution Compton scattering has proven to constitute an effective technique for probing the electronic structure of solids and liquids [2][3][4]. In recent years, merits and limitations of several quantum-mechanical methods have been assessed by comparing their predictions with accurate experimental Compton profiles (CP): (i) on the one hand, wave-functionbased methods, such as the reference Hartree-Fock (HF) and the perturbative MP2 (explicitly accounting for electron-electron dynamic correlation) ones, were found to satisfactorily describe most features of the EMD; (ii) on the other hand, the popular Kohn-Sham formulation of the density functional theory (DFT) has shown definite discrepancies with the experiment, systematically overestimating the anisotropy of the EMD, which can be traced back to its fundamental inability in satisfying the so-called virial theorem, −2hTi ¼ hVi (which in the HF method guarantees the balance between potential hVi and kinetic hTi contributions to the total energy of the system), by underestimating the kinetic energy [5][6][7][8][9][10].…”

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confidence: 99%

Anharmonic Thermal Oscillations of the Electron Momentum Distribution in Lithium Fluoride

et al. 2015

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Anharmonic thermal effects on the electron momentum distribution of a lithium fluoride single crystal are experimentally measured through high-resolution Compton scattering and theoretically modeled with ab initio simulations, beyond the harmonic approximation to the lattice potential, explicitly accounting for thermal expansion. Directional Compton profiles are measured at two different temperatures, 10 and 300 K, with a high momentum space resolution (0.10 a.u. in full width at half maximum), using synchrotron radiation. The effect of temperature on measured directional Compton profiles is clearly revealed by oscillations extending almost up to jpj ¼ 4 a:u:, which perfectly match those predicted from quantummechanical simulations. The wave-function-based Hartree-Fock method and three classes of the KohnSham density functional theory (local-density, generalized-gradient, and hybrid approximations) are adopted. The lattice thermal expansion, as described with the quasiharmonic approach, is found to entirely account for the effect of temperature on the electron momentum density within the experimental accuracy.

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Evidence of instantaneous electron correlation from Compton profiles of crystalline silicon

Cited by 27 publications

References 20 publications

Cryscor: a program for the post-Hartree–Fock treatment of periodic systems

Cryscor: a program for the post-Hartree–Fock treatment of periodic systems

Pressure-induced transitions in solid nitrogen: Role of dispersive interactions

Anharmonic Thermal Oscillations of the Electron Momentum Distribution in Lithium Fluoride

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