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People - Jeffrey Frey





Resumé
Jeffrey T. Frey
Department of Chemistry and Biochemistry
University of Delaware | Newark, DE 19711
Phone: (302) 831-3522 | Email: frey@chem.udel.edu | Office: 114 BRL



Education:
  • Graduated valedictorian, Lebanon High School (Lebanon, PA, 1995)
  • Graduated magna cum laude with Bachelors Degree in Chemistry, Lebanon Valley College of Pennsylvania (Annville, PA, 1999)
Computer Skills:
  • Proficient in several languages: C/C++/ObjC/Java, BASIC, various scripting languages.
  • Application design using Metrowerks PowerPlant and Apple Cocoa frameworks
  • Web design experience -- source-level HTML coding and graphics design with PhotoShop
  • System admistration: Linux (RedHat, PPC), Irix 6.5.x, Mac OS 7.5/8/9/X
  • Experience with: Gaussian98, WIEN97, CaChe Worksystem, Molden, Sybyl, LaTeX, Office, WordPerfect, PhotoShop, Illustrator, Mathematica

Research Interests
I am currently involved in several aspects of quantum chemical treatments of carbon nanostructures.
  • Using solid-state DFT code (WIEN97) I am explicitly treating a rolled nanotube lattice. Many prior calculations have been performed using quantization arguments applied to the electronic structure of sheet-graphite.
    • My preliminary results have been quite promising, reproducing the predicted metallic nature of the (3,3) SWNT. Current calculations on the (5,0) SWNT have proven interesting and I am currently using this nanotube to investigate the effects of nearest-neighbor tube distance in (5,0) SWNT bundles.
  • Investigation of methods for constructing better interaction potential functions between graphitic carbon and nitrogen/oxygen.
  • Investigation of curvature effects on the binding potential for nitrogen/oxygen on graphitic surfaces.

Resources
My Code Resources
TubeGen
In order to do solid-state calculations on the carbon nanotube systems, it was necessary to generate unit cells and subsequently the fractional coordinates for an arbitray chirality index. Using the definitions for the chirality and tubule translation vectors (found in Science of Fullerenes and Carbon Nanotubes, Dresselhaus, Dresselhaus, and Eklund) the TubeGen program was developed to turn the two chirality index values into a structure file which can be submitted to the WIEN97 FP-LAPW package. I've continued to modify the program as my own requirements change, so in its current incarnation it includes the following runtime options which the user may specify:
  • Nearest-neighbor C-C distance
  • Padding margin around atomic basis of cell
  • Two types of lattices:
    • Planar sheet in cubic cell
    • Tubular structure in hexagonal or cubic cell
  • Fractional or Cartesian translation of atomic basis
  • Export of cell to either a WIEN .struct file or a Gaussian .com file

The latest version of TubeGen (3.0) was rewritten to use the new CrystalCell C++ class. The class allows one to create an arbitrary cell, convert fractional coordinates in the cell to Cartesian coordinates (and vice versa), and add atoms to form the atomic basis for a crystal. To demonstrate the use of the class, two demo programs are included in the current TubeGen distribution: diamond and graphite. The former propogates a diamond crystal cell to generate Cartesian coordinates, the latter a graphite crystal cell.

Get the code!
Visit my web site for information on TubeGen.
STIGMA
The stigma program was created as an extension of a project by another member of the Doren Research Group. The program uses a Gaussian checkpoint file -- which inherently contains information about the molecule, basis set, and molecular orbitals -- and the Tersoff-Hamann s-wave-tip model to create a theoretical STM image in a user-specified scan plane. The program supports both constant-height and constant-current imaging methods.

The STIGMA web site contains an online User's Manual as well as some sample images produced by the code.

Visit the STIGMA web site.