Quantum Monte Carlo for the x-ray absorption spectrum of pyrrole at the nitrogen K-edge

Journal Article · Sat Apr 14 00:00:00 EDT 2012 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.3700803· OSTI ID:22047194

Zubarev, Dmitry Yu; Austin, Brian M ^[1]; Lester, Jr, William A ^[1]

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1. Kenneth S. Pitzer Center for Theoretical Chemistry, Department of Chemistry, University of California Berkeley, Berkeley, California 94720-1460 (United States)

Fixed-node diffusion Monte Carlo (FNDMC) is used to simulate the x-ray absorption spectrum of a gas-phase pyrrole molecule at the nitrogen K-edge. Trial wave functions for core-excited states are constructed from ground-state Kohn-Sham determinants substituted with singly occupied natural orbitals from configuration interaction with single excitations calculations of the five lowest valence-excited triplet states. The FNDMC ionization potential (IP) is found to lie within 0.3 eV of the experimental value of 406.1 {+-} 0.1 eV. The transition energies to anti-bonding virtual orbitals match the experimental spectrum after alignment of IP values and agree with the existing assignments.

• OSTI ID: 22047194
• Journal Information: Journal of Chemical Physics, Vol. 136, Issue 14; Other Information: (c) 2012 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ABSORPTION SPECTRA
CONFIGURATION INTERACTION
EXCITED STATES
GROUND STATES
MONTE CARLO METHOD
NITROGEN
PYRROLES
X RADIATION
X-RAY SPECTRA