Theoretical Prediction of Vibrational Circular Dichroism Spectra of R- Glyceraldehyde, R-Erythrose, and R-Threose. 2. Development of a Procedure to Scale the Force Constant Matrix Expressed in Terms of Internal Coordinates

Abstract

A very important objective of the Detection Directorate at the U.S. Army Edgewood Research, Development and Engineering Center is the remote detection of biological materials in the field. One line of thinking, currently being followed, is the recognition that sugars are distinguishing features of biological materials. In Part I of this study, the theoretical prediction of the vibrational circular dichroism (VCD) of the 3 and 4 carbon sugars R- glyceraldehyde, R-erythrose, and R-threose is considered. The calculational procedure used involves determination of the frequencies corresponding to the normal modes of vibration. Since calculated frequencies at the Hartree-Fock level are typically 10% too high, some form of scaling of the frequencies or the force constant matrix is required for quantitative agreement with experimental measurements. In Part II of this study, a scaling method is described, and three key FORTRAN computer programs are presented. Basically, the force constant matrix in internal coordinates at the 6-31G HF level of calculation is scaled to the calculated 6-31G MP2 level of calculation. The force constant matrix in terms of Cartesian coordinates can be determined from a matrix transformation, originally shown by Pulay, involving the force constant matrix in terms of internal coordinates. The scaling constant for each off-diagonal element of the force constant matrix was determined by using the geometric mean Q sub ij = (Q sub i)(Q sub j))(1/2) of the diagonal scaling constants Q sub i and Q sub j. Vibrational circular dichroism, Scaling of force constant matrix.

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Document Details

Document Type
Technical Report
Publication Date
Nov 01, 1993
Accession Number
ADA284305

Entities

People

  • Daniel Zeroka
  • James O. Jensen
  • Janet L. Jensen

Organizations

  • Battelle Memorial Institute

Tags

Communities of Interest

  • Air Platforms

DTIC Thesaurus Topics

  • Agreements
  • Aldehydes
  • Cartesian Coordinates
  • Chemistry
  • Computer Programs
  • Computers
  • Detection
  • Dichroism
  • Dihedral Angle
  • Engineering
  • Frequency
  • Identification
  • Information Systems
  • Procedures (Computers)
  • Spectra
  • Standards
  • Vibration

Fields of Study

  • Physics

Readers

  • Approximation Theory.
  • Linear Algebra
  • Quantum Chemistry