Theoretical Prediction of VIbrational CIrcular Dichroism Spectra of R- Glyceraldehyde, -Erythrose, and R-Threose. 1. Computational Results
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. Part I of this study reports on the theoretical prediction of the vibrational circular dichroism (VCD) of the 3 and 4 carbon sugars - R- glyceraldehyde, R-erythrose, and R-threose. The procedure involves optimization of geometries at the 3-21G HF and the 6-31* G HF levels and the subsequent determination of normal mode frequencies and rotational strengths to provide a nonscaled force constant result. To implement a scaling procedure, 8 small molecules containing 4-12 atoms were studied. Optimized geometries, frequencies and force constant matrices were determined based on calculations at the 3-21G HF, 3-21G HF, 6-31G* HF, and 6-31G* MP2 levels of calculation. A set of scaling constants were determined by scaling 6-31G* HF calculated diagonal force constants to the 6-31G* MP2 level calculations. The scaling constant for each off-diagonal element of the force constant matrix was determined by using the geometric mean Q sub ij = (QiQj) sup 1/2 of the diagonal scaling constants Qi and Qj. Couplings of various off-diagonal elements of the force constant matrix are reported. These scale factors were used to predict the VCD spectrum for the 3 sugars under study. Vibrational circular dichroism, R-erythrose, Scaling of force constant matrix, R-threose.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 1993
- Accession Number
- ADA284671
Entities
People
- Daniel Zeroka
- James O. Jensen
- Janet L. Jensen
Organizations
- Lehigh University