skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Relative Raman Intensities in C6H6, C6D6, and C6F6: A Comparison of Different Computational Methods

Abstract

In order to determine which models can best emulate Raman spectra, the accuracy of various computational methods (Hartee-Fock, MP2, CCSD, CAS-SCF, and several types of DFT) for predicting relative intensities in the Raman spectra of C6H6, C6D6, and C6F6 were compared. In particular, the predicted relative intensities for v1 and v2 were compared with relative intensities measured by an FT-Raman spectrometer. While none of these methods excelled at this prediction, Hartee-Fock with a large basis set was most successful for C6H6, and C6D6, while PW91PW91 with the aug-cc-pVTZ basis set was most successful for C6F6.

Authors:
; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org.:
USDOE
OSTI Identifier:
985078
Report Number(s):
PNNL-SA-46036
Journal ID: ISSN 1432-881X; ISSN 1432-2234; 3524; KP1704020; TRN: US201016%%1664
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Theoretical Chemistry Accounts, 117(2):283-290; Journal Volume: 117; Journal Issue: 2
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 97 MATHEMATICAL METHODS AND COMPUTING; ACCURACY; FORECASTING; RAMAN SPECTRA; BENZENE; DEUTERIUM COMPOUNDS; ORGANIC FLUORINE COMPOUNDS; CALCULATION METHODS; HARTREE-FOCK METHOD; Environmental Molecular Sciences Laboratory

Citation Formats

Williams, Stephen D., Johnson, Timothy J., Gibbons, Thomas, and Kitchens, Christopher L.. Relative Raman Intensities in C6H6, C6D6, and C6F6: A Comparison of Different Computational Methods. United States: N. p., 2007. Web. doi:10.1007/s00214-006-0135-z.
Williams, Stephen D., Johnson, Timothy J., Gibbons, Thomas, & Kitchens, Christopher L.. Relative Raman Intensities in C6H6, C6D6, and C6F6: A Comparison of Different Computational Methods. United States. doi:10.1007/s00214-006-0135-z.
Williams, Stephen D., Johnson, Timothy J., Gibbons, Thomas, and Kitchens, Christopher L.. Thu . "Relative Raman Intensities in C6H6, C6D6, and C6F6: A Comparison of Different Computational Methods". United States. doi:10.1007/s00214-006-0135-z.
@article{osti_985078,
title = {Relative Raman Intensities in C6H6, C6D6, and C6F6: A Comparison of Different Computational Methods},
author = {Williams, Stephen D. and Johnson, Timothy J. and Gibbons, Thomas and Kitchens, Christopher L.},
abstractNote = {In order to determine which models can best emulate Raman spectra, the accuracy of various computational methods (Hartee-Fock, MP2, CCSD, CAS-SCF, and several types of DFT) for predicting relative intensities in the Raman spectra of C6H6, C6D6, and C6F6 were compared. In particular, the predicted relative intensities for v1 and v2 were compared with relative intensities measured by an FT-Raman spectrometer. While none of these methods excelled at this prediction, Hartee-Fock with a large basis set was most successful for C6H6, and C6D6, while PW91PW91 with the aug-cc-pVTZ basis set was most successful for C6F6.},
doi = {10.1007/s00214-006-0135-z},
journal = {Theoretical Chemistry Accounts, 117(2):283-290},
number = 2,
volume = 117,
place = {United States},
year = {Thu Feb 01 00:00:00 EST 2007},
month = {Thu Feb 01 00:00:00 EST 2007}
}
  • We analyze the Raman-scattering response in a two-dimensional d{sub x{sup 2}{minus}y{sup 2}}-wave superconductor and point out a strong suppression of relative intensity in the screened A{sub 1g} channel compared to the B{sub 1g} channel for a generic tight-binding model. This is in contrast with the observed behavior in high-T{sub c} superconductors. {copyright} {ital 1997} {ital The American Physical Society}
  • Liquid chromatography coupled with mass spectrometry (LC-MS) is widely used to identify and quantify peptides in complex biological samples. In particular, label-free shotgun proteomics is highly effective for the identification of peptides and subsequently obtaining a global protein profile of a sample. As a result, this approach is widely used for discovery studies. Typically, the objective of these discovery studies is to identify proteins that are affected by some condition of interest (e.g. disease, exposure). However, for complex biological samples, label-free LC-MS proteomics experiments measure peptides and do not directly yield protein quantities. Thus, protein quantification must be inferred frommore » one or more measured peptides. In recent years, many computational approaches to relative protein quantification of label-free LC-MS data have been published. In this review, we examine the most commonly employed quantification approaches to relative protein abundance from peak intensity values, evaluate their individual merits, and discuss challenges in the use of the various computational approaches.« less
  • lntensities of the Raman lines of the totally symmetric vibrations of neopentane C(CH/sub 3/)/sub 4/ and deuterated neopentane C(CD/sub 3/)/sub 4/ in the gaseous state are determined photographically relative to the intensity of the v/sub 1/ line of CF/sub 4/ ,used as an internal standard. Assuming the simple Wolkenstein bond-polarizability theory, observed intensities are used to derive complete force -fields for the totally symmetric class of vibrations, and it is found that no such field can account satisfactorily for all the intensities as well as all the frequencies. The simple Wolkenstein theory is thus shown to be inadequate. Knowledge ofmore » the intensities of C(CD/sub 3/)/sub 4/permits for the first time a test of the modification of the theory in which Wolkenstein's assumption, that the polarizability of a bond is not affected by a change of bond orientation, is abandoned. Using an improved 4paraimeter field, the modified theory is found to succeed where the simple theory fails. (auth)« less
  • The mutual interactions of two copropagating laser beams at a relative phase are studied using a two-dimensional fluid code. The interactions are investigated in underdense plasma at selected beam configurations and beam parameters for two separate nonlinearities, i.e., the ponderomotive and the relativistic nonlinearity. The selected beam configurations are introduced by different initial transverse spot size perturbations (finite and infinite) and different initial transversal intensity distributions (nonuniform and uniform) over those spot sizes and the selected beam parameters are given by different initial beam intensities relevant to each nonlinearity. In the ponderomotive nonlinearity, simulation results show that no mutual interactionsmore » are demonstrated between the copropagating beams regardless of the initial beam configurations and parameters. In nonlinear relativistic simulations, the mutual interactions between the beams are clearly observed, a mutual repulsion is formed in the presence of initial intensities that are nonuniformly distributed over finite spot sizes, and an effective strongly modulated mutual attraction takes places in the presence of initial intensities that are uniformly distributed over infinite spot sizes. Moreover, it is found in these simulations that increasing the initial beam intensities improves the attraction properties between the copropagationg beams.« less