Chemiccrl Educcrtion: Software Abstracts for Volume IIIB, Number 2 Numerical Solutions for Schroedinger's Equation Frank Rioux Saint John's University Collegeville, MN 56321 Four comnuter nroarams (or four spreadsheet templates) are used in f 5 studentkxercises that Govide an introduction to the numerical approach for solving Schroedinger's equation. The exercises-are suitable for ;se in the traditional physical chemistry sequence. The numerical technique, a modified Numerov finite-difference algorithm, is accessible to undergraduates, easy to program, and reasonably accurate. Combined with the graphics capability of a personal computer, the numerical method provides a powerful pedagogical tool for teaching quantum theory. The 25 exercises include landmark cases for which students will be able to find textbook analytical solutions, cases that permit comparisons with the results of perturbation theory or the variation method, and cases where no analytical solution can be obtained. In addition to the standard problems the exercises cover: umbrella inversion of ammonia, hindered internal rotation in ethane, the LennardJones 6-12 potential, alpha-particle decay, the Morse potential, and the quark-antiquark interaction in charmonium. QuickBASIC programs and Lotus 1-2-3 templates have been prepared for each exercise. Programs or templates and the accompanying workbook of exercises provide the basis for a laboratory-like supplement to lecture presentations on the fundamentals of quantum theory and its applications in chemistry and physics. The exercises are self-contained, allowing instructors maximum flexibility in adapting the package to a variety of course structures and individual preferences.
Pop-Up Units Converter Gordon Fllby Martin Klusmann University of Karlsruhe and Nuclear Research Center 75 Karlsruhe, West Germany This memory-resident (TSR) program can he called upon with a single keystroke from any other MS-DOS program. I t provides conversion factors and calculations among a variety of different units. In addition i t serves as an example of how to create a program that can remain in memory while other programs are running, thereby being available a t all times to program users.
ChemCalc: A Scientific Calculator Robert D. Allendoeller S U N Y Buffalo Buffalo.NY 14214-3094 ChemCalc is a scientific calculator program that can be used stand-alone or incorporated intoother software written 770
Journal of Chemical Education
in BASIC. Like a typical scientific calculator it allows students to evaluate arithmetic expressions entered from the keyboard; numbers and operators are entered; and pressing return gives the numeric result of the calculation. In addition, ChemCalc knows the atomic weights of the elements, Avogadro's number, and some useful constants. Whenever an atomic symbol is found in the expression to be evaluated, the atomic weight is substituted. Likewise, the gas constant is substituted for R, Avogadro's number is substituted for A, 3.14159 is substituted for II, etc. This makes easy entry of expressions to calculate the weight percentage of an element in a molecule or the molecular weight of a compound.
About This Issue John W. Moore University of Wisconsin-Madison Madison, WI 53706 This issue contains two programs that will be useful in any chemistry course from the introductory level on and one designed for physical chemistry. All involve the computer as a calculator in one way or another. Pop-Up Units Converter allows a chemist or student to call u p at any time a calculator that will convert from one unit to another for the same physical quantity. ChemCalc allows a variety of calculations to be done on individual numbers or on pairs of numbers; it is usable stand-alone or as part of a CAI or drill-and-practice program. Both will find use in a variety of situations encountered daily by chemists and chemistry teachers. Numerical Solutions for Schroedinger's Equation goes beyond conventional textbooks and teaching methods in physical chemistry, providing a general method for solving Schroedinger's equation. Numerical solutions (as compared to closed-form analytical solutions, the variation method, or perturbation theory) provide an accurate and mathematically simple alternative that has important pedagogical strengths. Numerical methods work very well for a wide range of applications and are essential when exact and approximate analytical techniques fail or are difficult to apply. Frank Rioux's programs, spreadsheet templates, and exercises fill an important gap in the current pedagogical literature of physical chemistry. Hardware Requlrements Programs in this issue are supplied on 5.25-in. disks and will run under MS-DOS (IBM PC DOS) version 2.1 or later. Numerical Solutions to Schroedinger's Equation requires 512K RAM, one disk drive, and a Color Graphics Adapter (CGA) or compatible graphics adapter for the BASIC programs; the spreadsheet templates can be run on any computer that will run Lotus 1-2-3. (Lotus 1-2-3 requires DOS 3.0 or higher and a t least 256K RAM, but the more memory the better. A graphics adapter will also he needed. Lotus 1-2-3 is not su~nlied-vou must have vour own coov .. .. or Durchase . one., VhemCnlc and Pop-1.1) (!nits Con\.erter require 256K HAM and one disk drive. To use ChernCalc~as a iulmrutine in your own program you will need BASIC.
