update the experiment each year by replacing questions older than eight years with ones from the current year. This also protects the magazines from overuse. After an introduction to the library and a discussion of the "experiment," students work individually on their "experiment" during the rest of the laboratory. A chemistry instructor answers questions and guides students, thus also assisting the library staff. The "exp&ment" has seven parts:
program with accompanying documentation and answers for all the questions is available for $3.00, or a cassette tape with corresponding answers and documentation is available for $10.00. An exchanee of chemistrv and environmental science programs is also disired by the author.
Part A: For the indicated question, students are asked to write a
complete bibliography. They are told that they will find all books in the card catalog.There are twenty-fivequestions; a student answers only one. For example, the following questions might be given: (1) To study the principles of polymer chemistry, one should select whnt hook? (21 If vuu ore interested in learning nhout some the chemistry of rhe Manhattan l'rojrct, to whnt hook will you turn" ~~~~
Computer Programs for Introductory Quantum Chemistry Bhatrav D. Josh1 State University College at Geneseo Geneseo. NY 14454
~~
Port B: Using the "Reader's Guide to Periodical Literature" or a
December index, the students are asked to write the complete literature reference for the following articles: (1) Grinstead, R. R., "Bottlenecks." (2) Flath, P. C. and R. Uhorehak, "VersusNersus-A Lab Students Don't -.~ . - -D~end.'' ~ ---There are 57 questions in this section; a student is assigned two. (Use Sciquest, Scientific American, Enuironment, or THIS ~
Part C and Part D: Both of these parts involve the four journals
previously indicated. A description of the article is given and students start with kevwords tosearch for the article. Part C has 44auestions from ~ciouebt.Scientific American or Enuironment. A &dent anmight be given: (1) A 1973article discusses the problems of removing CO from auto exhaust. Has success been achieved in this project? Cite the article. (2) Cite a 1977 article by an author from one of our sister two-year colleges in northern New York on planning a hazardous materials course for local firemen. Name the author's college affiliation. Port E: From a list of twenty-five terms, a student is asked to define
one term and give the complete reference. The answer will he found in one of many reference works available in the library. The following are terms that might be used: (1) Define Sulliuon's Test. (2) Define smoltite. Port F: Fnm a list of twrnry-re\.rn quesriona a ~tudentmust search t h o "Handhook of Chemirtry and Physics" for the answer tu hi* assigned quesuon. For example,he might he asked the Idlowing qurs-
tions: (1) Which is denser-water
or 4-methyl-2-pentanone? (2) How many BTU's in an erg?
Port G: Similarly, Part Grequirea a student to search the "Handbook" for the answers to one of four different tvnes of ouestiaus. For ex-
..
ample, the following questions might he given: (1) The solubilityof 1-alanineis -grams1100 grams of water at 25%. (2) Constants for babassu oil are specific gravity -iodine value saponification number melting point T h e "exoeriment" has been accepted and enioved bv the majority oE students over the past tkn years. ~ o scomment t about finding new (to them) ways of searching the literature. The largest problem for me has been the mechanics of making sure each student receives a different set of questions. This year I put all of the questions into one computer program and then printed sixty lists of randomly selected questions. With my printer I have hard copy, but it could be done with a CRT if no printer were available and the question' numbers copied onto a pretyped form. The program is written in BASIC, specifically for a Model I, Level 11, 16K TRS-801 microcomputer. A listing of the
' TRS-80 is a trademark of the Tandy Corporation.
James E. Ellers State University College at Brockport Brockport, NY 14420 For the past two years we have been involved in the development of a set of comouter oroerams in auantum chemistrv. The purpose of this prbject & tocreate a facility that will free the student from time-consuminamathematics so that he can concentrate on concepts, pri&iples, and techniques of quantum chemistrv. T h e set of computer programs we have developed generates data, solves equkions, graphs solutions, and asks leading questions. I t also includes numerous lessons and drills on qu-&tum chemistry concepts and mathematical methods used in the study of quantum chemistry (16). The ouantum chemistrv- nroerams oackaae is beine de. signed for real time operation from interactive computer terminals by students with no required programming skills. T h e programs themselves are written either in interactive FORTRAN to run on PRIME 400, or in APL to run on ITEL AS16 under OSIVS1. The package contains service routines, limited task routines, teaching routines. drill-practice routines, and monitor and control [outines. 1n able 1we present an alphabetical listing of all programs developed and tested thus far. The following abbreviations are used in Table 1: RR for "rigid rotor," P I B for "particle in a box," and SHO for "simple harmonic oscillator." Listings of the programs will be made available to interested readers for a $5.00 fee to cover duplication and mailing charges. Please contact B. D. Joshi. This work is suooorted. in part. bv grants from the State Cniversity of ~ e w i ' o r k~ & r c h kida at ion: # 125-1006A, it 12WWtiH. It 1%-JW8A. and it 125-4WXH.Ihanks are due 1)r. I.w'l'.lksant ot'the (;en&(, (.ornputing Center tor his continu(rui and enthuiiaitic iupuort of this work. B. D. doshi is grateful to Barbara Joshi fo; h e r encouragement and unflagging support.
Extended Hiickel M.O. Calculations for Classroom Demonstration John P. Cheslck Haverford College, Haverford, PA 19041 Molecular orbital theory in various forms is the basis for discussions of bonding and structure in manv chemistrv courses. Simple ~ i i c k e l i h e oisr ~used for discussions of plan& pi-electron svstems, with modifications oermittine discussion bf the effects of hetero (noncarbon) atoms on thepi-electron molecular orbitals, energies, and pi-electron charge densities. McGrath. Kroeeer. " , and Dunn (17) have described a BASIC program package to explain the theory with a small computer Volume 59
Number 6
June 1982
517
Table 1. Computer Programs for an Introductory Quantum Chemistry Course #
Program
1 ANGMOM 2
CALC
3
CLPROB
4 5
CONPOL CONTOUR
6
COSPOT
7
COSPRT
9 10 11 12
EHO ENERGY EPlB EPOTWL
13 14
ETRANS EXPAND
15 16 17 18
FAL FL FPSi FREQ
19 20 21 22 23 24 25 26 27 28 29 30 31 32 33
FX(E) GOCLPROB GOCOSPOT GOCOSPRT GOEPOTWL GOFAL GOGRAPH GOHERM GOPERT GOPOLYENE GOROTPROP GORSH GOSiMP GRAPH HERM
#
Description Calculates the angular momentum of a PR. Used by EXPAND to calculate various approximations to e' in terms of PlB wave functions using the quantum mechanical expansion theorem. Calculates SHO's probability of being in the classically forbidden reaion. " Applies the PIE model to conjugated poiyenes. Plots twdimensianal elecbon-density contours of atomic orbitals. Calculates and stores the first-order perturbed wave function of a PIB with cosine bottom. Applies first order perturbation theory to the problem of a PIE with a cosine bottom. Evaluates the first derivative of energy of a PIB with finite depth. Calculates the energy of a SHO. Calculates the energy of a RR Calculates the energy of a PIB. Calculates and tabulates the energy of a PIE with finite depth. Calculates energies of allowed rotational transitions. A graphical illu~trationof the quantum mechanical expansion W r e m . Calculates unnormaiized as-iated legendre functions. Calculates unnormalired legendre functions. Calculates the PIB wavefunction. Calculates the fundamental vibrational frequency of a diatomic molecule given the force constant. evaluate^ the energy of a PIE with finite depU1. Interactive "driver"for CLPROB. Interactive "driver" far COSPOT. interactive "driver" for COSPRT. Interactive "driver" lor EPOTWL. Interactive ''driver" for FAL. Interactive "driver" for GRAPH. Interactive "driver" for HERM. interactive "driver" for PERT. Interactive "driver" for CONPOL. Interactive "driver" for calculating properties of an RR. Interactive "driver" for RSH. Interactive "driver" for SIMP. Plats f l X ) versus X, given the values. Calculates Hermite polynomials.
system. Nnnplanar systems, including sigma bonding effect*, are handled at about the same level of approximation by extended Huckel theory, which uses valen-& orbital ionization energies as input parameters in conjunction with atomic orbital overlap integrals. The use of this level of approximation to represent the construction of single determinant of L.C.A.0:M.O. (linear combination of atomic orbitals-molecular orbital) kave functions has been discussed in detail by Gavin (18)as a method that provides insights into stereochemistry and bonding with a minimum of computation. Baird (19) has more recently repeated many of Gavin's comments with further elaboration. The essential results of more elaborate molecular orbital results are a t least semiquantitatively described using extended Huckel theory. The availability of portable, powerful, and relatively inexoensive microcornouter svstems. which can disnlav invut and butput operations bn mo~itors vkihle to a class or lecture room (20), makes possible the classroom illustration of such calculations. These can he a striking addition to the lecture oresentations of molecular orbital theorv and the uses of &uputational results from this theory. These small computer svstems also Dromote student access and usaee for individual &k. We ar; here reporting the operation n"ii availnhility of an interactive program to do extended Huckel calculations for di- or triatomic molecules conmining any comhinntion of the elements hydrngen through argon. Thus, changes in orbital
. " .
518
Journal of Chemical Education
Prcgrem HNK
Description
RRPROGS RSH STATES6 THYDRO TRADiA XBAR X2BAR XiNUM
Calculates the coenicients which determine the first order wave function far a PIE with sloping bottom. Calculates relative populations of states of an RR. Interactive "driver" far HOOlS. Calculates the force Constants for a diatomic molecule using the SHO approximation. Generates tables and plots of radial hydrogenic wave functions and their squares. Calculates the value of (p2)for a PIB. Applies the first arder perturbation theory to a PIB with sloping bottom. This is an interactive program dealing wim variws aspects 01 quantum mechanical principles and uses the numemus PIB programs to illustrate them. Interactive "driver" for calculating the properties of a PlB. Calculates and plots J/"(.rJ and $b,,(~)~for a PIB. Calculates the frequency of the radiation emitted by a PiB during a transition: n, n*. Keeps statistical record of a student's pwformance during a given interactive session. calculate^ the wave function for a SHO. Calculates ( A p ) far a PIE. Calculatesthe bonMistance for a diatomic moleculeusing the RR approximation. Calcuktes and tabulates lhe atamic two elemon integals aver hydrogenic functions. Calculates the relative population of states for an FIR. C a I c ~ I a t erotatiand ~ freouencv . . and the oeriod of rotation of an RR. Calculates properties of an RR. Calculates the real spherical harmonics. Generates Russel-Saunder's atomic term-symbols Calculates Laguerre polynomials. Calculates the radial hydrogenic wave functions. Calculates ( x ) for a Pie. Calculates (9) for a PIB. Generates and tabulates the integrals
XUNCER
for SHO wave functions. Calculates (Ax) for a PIB.
HODIS HODIST HOOKE HYDRO P2BAR PERT PlBOOl
PIBFNS PIBFPLOT PlBNU PIBSTA PSHiO PUNCER R R12 REWlS RHOTAU
-
energies within a group of the periodic table as well as cornparismi of resulu u,ith atoms of different groups niay he seen. This has heen written in BASIC for such n nnnpurer system. Valence shell \ and p atomic orbitals are used, with rariahle molecular geometry~For example, calculations of dihydrides of the formula HAH can be made with varying . . bond angle: comparison of results gives the Walsh diagrams prrriouily discussed (18, 1.9). Orhital energies, acts of atomic orhital coefficienu for the mnlerular o r b i ~ l ia. ~ l dthe overlxo internal matrix used are available as numerical output. ~ h e ' s ecanbe auicklv examined or recorded for sevarate use as sueeested .... hy theierrl of thr course treatment. he mmt generally useful feature is a graphic disolnv of thr orbital correlation diagram showing both atomic and molecular orbital energies, an; optional connections drawn between the molecular orbitals and their principal constituent atomic orbitals. Execution time for the calculations is short enough to permit use during a c l ~ s r u o t ndiswsiim. Table 2 givesthe n,mpu~t& time, that needed to find the eigenvalues and eigen\.ectms of the Hiickel matrix for various size oroblems us& an Annle 11-plus computer system. The total execution time should be ereatlv reduced if a comoiled laneuaee such as FORTRAN or P A S ~ A were L to be &ed. Thys &gram was written in BASIC, but the conversion to FORTRAN should he very simple. BASIC is the most widely available programming language for the personal (micro) computer.
-~~ . ~ . ~
Table 2. Execution Tlme for Elgenvalue-Eigenvector Calculationa
Ploning PotentiometricTitration Data Using an Apple II
NO.
Vinay Kumar and John I. McAndrews Northern Kentucky University. Highland Heights, KY 41076
orbitals
HA HAH (nonlinear)
A0 HA0 (linear) ABC (linear) ABC (nonlinear)
5 6 8 9 12 12
15 35 50 60 170 210
A and Bare any of the elemen13 He through Ar.
Apple 11-plus computer system.
After callina u p the promam, the user inputs the chemical symbols, when prompted;for the two or three atoms in the molecule. Interatomic distances obtained from an internal table of atomic radii are offered to the user, who may either accept or modify the values. Input of the bond angle, if a triatomic molecule is being donelthen concludes the required data specification. The first outout obtained is the atomic orbital overlap integral matrix, which can be examined as part of a discussion of molecular symmetry or recorded for later use with molecular orbital coefficients if a charge density or bond order population analysis is to he done as a separate exercise. The molecular orbital energies and coefficients are then produced, sorted hv enerev. At the user's convenience the orbital enerw diagram-is di&layed. Connections are drawn between each molecular orhital energy level and the energy levels of constituent atomic orbitals for which the molecular orbital coefficient exceeds a chosen minimum value. This may he repeated with different choices for the minimum. The enerw and wf'ficients for a n y molecular orbital may hL. redirplayed, along with the correlation diagram, to permit special discussion or comment on orbital symmetry and the relative importance of different atomic orbitals in a particular molecular orhital. A choice is then made to stop or to reload the program and try another molecule or another geometry for the same molecule. The program was written in floating point BASIC (Applesoft) for use with an Apple 11-plus computer and consists of the main Droeram and subroutine senments for overlap integral calcuiat~ons,the calculation of the U-I transformation matrix, and the Jacobi eiaenvector-eigenvalue routine. The of the main program sets up the arrays used as last starting and ending points of the lines drawn in the graphics display. The whole program system consists of 480 BASIC numbered statements, not counting comments, and dimensioned variable arrays totalling 601 words. The BASIC program statements require 10.5 K bytes and the variables rem i r e 3.8 K bvtes of storaee. The Apple hizh-resolution graphics call do& wipe out t h i part of thhprogr& containing the subroutines after their use has heen completed: hence the program is reloaded after each complete molecular calculation. The program is also readily segmented t o save space, if necessary variables and arrays are saved. The graphics usage assumes the availability of a four-line text window and a point-toypoint straight line plot command in BASIC, and should be readily adaptable to other microcomputer systems. A Pascal cornoiled version is olanned. A program &ing, documeniation, including text giving axis conventions, and a master diskette with the Applesoft BASIC program file produced using Apple DOS version 3.3,16-sector format, is available for $15.00 to cover costs. The disc includes one copy of the program with program comments and an otherwise identical copy with comments. Documentation with program listing is available for $5.00 without the program disc. Send a check for the amount payahle to John Chesick, Haverford College, Haverford, PA 19041.
Jon W. Mauch Maderia High School, Maderia, OH 45243 For n great many years, porenriometric firrations involving acid-hare andlm redox reactions have been one of the traditional experiments for chemistry students in the quantitative analysis laboratory courses. Whereas the experimental procedure for doing a potentiometric titration is easy, enjoyable, and consumes relatively little time, the accompanying calculations for obtaining the first and second derivative plots take up a lot of the students' time. In order to save that valuable time and to show the students how a microcomouter can he used to obtain the titration plots, we have developed a program called PLOTTER. It is written in Ao~lesoftBASIC i n d h a s been successfully used by our studenis on an Apple I1 microcomputer. The program has the capability of handling both pH and millivolt (mv) data. In addition, it is versatile enough to do the following: display dl entered data inn n TV monitur screen and allow the srudmt to make corrections (11) rolrulare and display pvintwiit ,,nlues of che first and second derivatives (c) d a w the student to see the following three plots in color graphics on the screen: (i) pH (or mv) versus mL of titrant (ii) first derivative versus mL of titrant (Fig. 4) (iii) second derivative versus mL of titrant (Fig. 5) (d) indicate the volume needed to reach the equivalence point. In)
screen
Figure 5. Display of
second
derivative versus mL of titrant plot
on the TV
screen.
Volume 59
Number 6 June 1982
519
