Obtaining Hartree–Fock and density functional theory doubly excited states with Car–Parrinello density matrix search

Liang, Wenkel; Isborn, Christine M.; Li, Xiaosong

doi:doi:10.1063/1.3266564

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Universal nonexponential relaxation: Complex dynamics in simple liquids

The dynamics of the noble-gas liquids underlies that of all liquids making them an important prototypical model system. Using optical Kerr-effect spectroscopy we show that for argon, krypton, and xenon, both the librational and diffusional contributions to the spectrum are surprisingly complex. The diffusional relaxation appears as a stretched-exponential, such as widely found in studies of structured (e.g., glass-forming) liquids and as predicted by mode-coupling theory. We show that this beha...

Semiclassical electron correlation operator

The concept of the correlation operator, introduced 10 years ago as a possible method to model the electron correlation effects with single determinant wave functions [ Rassolov, J. Chem. Phys. 110, 3672 (1999) ], is revisited. We derive a semiclassical limit of the correlation operator in weakly correlated systems and give its coordinate space representation. Application of this operator to the atomic systems, such as computations of energies of the neutral atoms, energies of the cations, and ...

The calculation of doubly excited states is one of the major problems plaguing the modern day excited state workhorse methodology of linear response time dependent Hartree–Fock (TDHF) and density function theory (TDDFT). We have previously shown that the use of a resonantly tuned field within real-time TDHF and TDDFT is able to simultaneously excite both the α and β electrons to achieve the two-electron excited states of minimal basis H₂ and HeH⁺ [ C. M. Isborn and X. Li, J. Chem. Phys. 129, 204107 (2008) ]. We now extend this method to many electron systems with the use of our Car–Parrinello density matrix search (CP-DMS) with a first-principles fictitious mass method for wave function optimization [ X. Li, C. L. Moss, W. Liang, and Y. Feng, J. Chem. Phys. 130, 234115 (2009) ]. Real-time TDHF/TDDFT is used during the application of the laser field perturbation, driving the electron density toward the doubly excited state. The CP-DMS method then converges the density to the nearest stationary state. We present these stationary state doubly excited state energies and properties at the HF and DFT levels for H₂, HeH⁺, lithium hydride, ethylene, and butadiene.

Article Outline

INTRODUCTION
METHODOLOGY
1. Dampened velocity Car-Parrinello density matrix search (CP-DMS)
2. Local quantum harmonic oscillators
3. Lagrangian constraint and zero point reference
4. Unitary transformation real-time TDHF/TDDFT to propagate the electron density
RESULTS AND DISCUSSION
CONCLUSIONS

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KEYWORDS and PACS

Keywords

density functional theory, excited states, helium compounds, HF calculations, hydrogen neutral molecules, lithium compounds, molecule-electron collisions, organic compounds, positive ions, wave functions

PACS

31.15.xr

Self-consistent-field methods
31.15.ee

Time-dependent density functional theory
34.80.-i

Electron and positron scattering
31.50.Df

Potential energy surfaces for excited electronic states

ARTICLE DATA

Digital Object Identifier

http://dx.doi.org/10.1063/1.3266564

PUBLICATION DATA

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0021-9606 (print)

1089-7690 (online)

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American Institute of Physics

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