Pressure effects on the electronic and structural properties of molecules

Cruz, S. A.; Soullard, J.

doi:10.1016/j.cplett.2004.04.099

Cited by 53 publications

(29 citation statements)

References 24 publications

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“…The impact of spatial confinement on the molecular bond lengths is well recognized in the literature . Therefore, geometries of the investigated molecules were optimized both in vacuum as well as in the presence of confining potential using the CCSD/aug‐cc‐pVTZ method.…”

Section: Methodsmentioning

confidence: 99%

Benchmarking DFT methods on linear and nonlinear electric properties of spatially confined molecules

Chołuj

Kozłowska

Bartkowiak

2018

Int J of Quantum Chemistry

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The accurate evaluation of molecular electric properties still constitutes a challenge for density functional theory (DFT) methods. Moreover, some new issues appear, within this area of research, that require analysis. One of them concerns the electric properties of confined matter. This study aims at a quantitative evaluation of the performance of DFT framework in the description of dipole moment, polarizability, and first hyperpolarizability of the isolated and spatially confined molecules.The calculations were performed using a set of 35 exchange-correlation functionals. The reference data were determined employing the highly accurate CCSD(T) method. To mimic the effect of spatial confinement the cylindrically symmetric harmonic oscillator potential was applied. Based on the conducted research it was found that the behavior of the considered functionals substantially differs depending on the studied electric property and molecule. Moreover, it was observed that the strength of spatial confinement strongly influences the performance of DFT methods. K E Y W O R D Sdipole moment, exchange-correlation functionals, (hyper)polarizability, spatial confinement | I N T R O D U C T I O NOver the last decades the Kohn-Sham formulation of density functional theory (KS-DFT) [1] has become one of the mainstream formalisms among various electronic structure methods of modern quantum chemistry. Undoubtedly, it results from the favorable balance between the accuracy of the outcomes and the computational economy of this approach. Formally, the computational cost of DFT, which includes an approximate treatment of electron correlation, scales as N 3 (N denotes the number of electrons in the molecular system), while in the case of correlated wave function methods scaling factor is equal to, at least, N 5 AN 7 . Conversely, the well-known problem of DFT lies in the fact, that the exchange-correlation functional (XCF), being the only unknown term in the expression of the total energy, might be given exactly for the free electron gas, while in all other cases it has to be approximated. [2] Thus, various forms of XCF have been developed, building a hierarchy that is often represented by the rungs of metaphorical Jacob's ladder: [3,4] local spin density approximation (LSDA), generalized gradient approximation (GGA), meta-GGA, hybrid GGA/meta-GGA, and double hybrid GGA/meta-GGA. Unfortunately, although the functionals on higher rungs contain more complex ingredients there is no guarantee that utilizing them would provide an improvement across all types of physicochemical properties (geometry, energetics, thermochemistry, etc.) for different types of molecular systems. This is the main drawback of DFT in comparison to the wave function methods, which provide a systematic and transparent route toward gaining more accurate results. Accordingly, it is not surprising that benchmarking accuracy of various types of XCFs has become an important task in quantum chemistry. [5][6][7][8][9] In the course of examining DFT performance it has been fou...

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Section: Methodsmentioning

confidence: 99%

Benchmarking DFT methods on linear and nonlinear electric properties of spatially confined molecules

Chołuj

Kozłowska

Bartkowiak

2018

Int J of Quantum Chemistry

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“…We also note that the tGTO basis is simpler than the smoothly cut-off floating spherical GTO basis of Ref. 61 in the sense that their cut-off introduces a mixing of two symmetry types (e.g. s, d) in each basis function.…”

Section: B Truncated Gaussiansmentioning

confidence: 95%

Temperature-dependent behavior of confined many-electron systems in the Hartree-Fock approximation

2012

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Many-electron systems confined at substantial finite temperatures and densities present a major challenge to density functional theory. In particular, there is comparatively little systematic knowledge about the behavior of free-energy density functionals for temperatures and pressures of interest, for example, in the study of warm dense matter. As with ground-state functionals, development of approximate free-energy functionals is faced with significant needs for reliable assessment and calibration data. Here we address, in part, this need for detailed results on well-characterized systems. We present results on a comparatively simple, well-defined, computationally feasible but previously unexplored model, the thermal Hartree-Fock approximation. We discuss the main technical tasks (defining a suitable basis and evaluation of the required matrix elements) and give an illustrative initial application which probes both the content of the model and the solution techniques: a system of eight one-electron atoms with nuclei at fixed, arbitrary positions in a hard-walled box. Even this simple system produces physical behavior different from that produced by simple ground state density functionals used at finite temperature (a common approximation in the study of WDM).

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“…Thus far, numerous theoretical results presented in the literature demonstrate that spatial restriction significantly modifies nonresonant electric dipole properties of atoms and molecules. [9][10][11][12][13][14][17][18][19]23,24,31,32 In particular, it was reported that the values of effective linear polarizability (a) as well as second hyperpolarizability (g) decrease together with the increasing strength of orbital compression. 9,10,12,13,[17][18][19]31,33 On the other hand, the behavior of dipole moment (m) and first hyperpolarizability (b) differs depending on the topology of the confining environment and the system under consideration.…”

Section: Introductionmentioning

confidence: 99%

“…9,10,12,13,[17][18][19]31,33 On the other hand, the behavior of dipole moment (m) and first hyperpolarizability (b) differs depending on the topology of the confining environment and the system under consideration. 9,12,32,33 It should be underscored that there are only a limited number of theoretical studies concerning the evaluation of the molecular quantities that govern the NLO processes in the resonant regime upon confinement. 9 This work aims to fill the existing gap.…”

Section: Introductionmentioning

confidence: 99%

Two-photon absorption of the spatially confined LiH molecule

Kozłowska

Chołuj

Zaleśny

et al. 2017

Phys. Chem. Chem. Phys.

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In the present contribution we study the influence of spatial restriction on the two-photon dipole transitions between the XΣ and AΣ states of lithium hydride. The bond-length dependence of the two-photon absorption strength is also analyzed for the first time in the literature. The highly accurate multiconfiguration self-consistent field (MCSCF) method and response theory are used to characterize the electronic structure of the studied molecule. In order to render the effect of orbital compression we apply a two-dimensional harmonic oscillator potential, mimicking the topology of cylindrical confining environments (e.g. carbon nanotubes, quantum wires). Among others, the obtained results provide evidence that at large internuclear distances the TPA response of lithium hydride may be significantly enhanced and this effect is much more pronounced upon embedding of the LiH molecule in an external confining potential. To understand the origin of the observed variation in the two-photon absorption response a two-level approximation is employed.

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Pressure effects on the electronic and structural properties of molecules

Cited by 53 publications

References 24 publications

Benchmarking DFT methods on linear and nonlinear electric properties of spatially confined molecules

Benchmarking DFT methods on linear and nonlinear electric properties of spatially confined molecules

Temperature-dependent behavior of confined many-electron systems in the Hartree-Fock approximation

Two-photon absorption of the spatially confined LiH molecule

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