Fortran

To meet these conditions a special chemical programming language CHMTRN (Chemical Translator) was developed. By use of a special assembler - TBLTRN (Table Translator, written by Dr. Donald E. Barth), it was possible to convert the CHMTRN tables into specially encoded FORTRAN BLOCK DATA statements which could be loaded with LHASA or read in at run time. 

The basic approach of CHMTRN is that there are keywords (currently several hundred) that have 

If this name conflicts or duplicates that of some other chemical program, I apologize. The duplication is unintentional. 

ACS Symposium Series American Chemical Society Washington, DC, 1977. 

LHASA contains an interpreter called EVLTRN (Evaluate Transform) which decodes the bit patterns and performs the requested queries about the current structure or performs a specified operation. As an example, consider a line from the tables which says 

Given the concentrations of Na, Ca, Cl, and SO4 (as some combination of NaCl and Na2S04), this subroutine calculates the activity coefficients of Ca and SO4 and the activity of water, using the Pitzer equations and the parameters from Harvie and Weare (1980). The expression Uca +asoj- HjO tested 

Even readers not familiar with FORTRAN should be able to see how the many summation signs in the Pitzer equations are expanded into actual expressions, and how the many parameters fit in. The equations are broken up into terml, term2, etc., to correspond with the text in 15.7.2. Here are some comments which may help to understand the program. 

To make the program easier to read. Equation (15.38) in Chapter 15 is split into a number of terms which have separate statements in the program. These are as follows. 

SUBROUTINE pitzer (mNa,mCl,mCa,mS04,gainma Ca,gamma S04,aH20) 1 

PARAMETER REAL,PARAMETER REAL,PARAMETER REAL,PARAMETER REAL,PARAMETER REAL, PARAMETER REAL,DIMENSI0N(3),PARAMETER REAL,DIMENSI0N(3),PARAMETER REAL,DIMENSION(3),PARAMETER REAL,DIMENSI0N(3),PARAMETER 

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The calculation of vapor and liquid fugacities in multi-component systems has been implemented by a set of computer programs in the form of FORTRAN IV subroutines. These are applicable to systems of up to twenty components, and operate on a thermodynamic data base including parameters for 92 compounds. The set includes subroutines for evaluation of vapor-phase fugacity... 

The calculation of single-stage equilibrium separations in multicomponent systems is implemented by a series of FORTRAN IV subroutines described in Chapter 7. These treat bubble and dewpoint calculations, isothermal and adiabatic equilibrium flash vaporizations, and liquid-liquid equilibrium "flash" separations. The treatment of multistage separation operations, which involves many additional considerations, is not considered in this monograph. 

Evaluation of the activity coefficients, (or y for noncondensable components),is implemented by the FORTRAN subroutine GAMMA, which finds simultaneously the coefficients for all components. This subroutine references subroutine TAUS to obtain the binary parameters, at system temperature. 

The computation of pure-component and mixture enthalpies is implemented by FORTRAN IV subroutine ENTH, which evaluates the liquid- or vapor-phase molar enthalpy for a system of up to 20 components at specified temperature, pressure, and composition. The enthalpies calculated are in J/mol referred to the ideal gas at 300°K. Liquid enthalpies can be determined either with... 

The bubble and dew-point temperature calculations have been implemented by the FORTRAN IV subroutine BUDET and the pressure calculations by subroutine BUDEP, which are described and listed in Appendix F. These subroutines calculate the unknown temperature or pressure, given feed composition and the fixed pressure or temperature. They provide for input of initial estimates of the temperature or pressure sought, but converge quickly from any estimates within the range of validity of the thermodynamic framework. Standard initial estimates are provided by the subroutines. 

Both vapor-liquid flash calculations are implemented by the FORTRAN IV subroutine FLASH, which is described and listed in Appendix F. This subroutine can accept vapor and liquid feed streams simultaneously. It provides for input of estimates of vaporization, vapor and liquid compositions, and, for the adiabatic calculation, temperature, but makes its own initial estimates as specified above in the absence (0 values) of the external estimates. No cases have been encountered in which convergence is not achieved from internal initial estimates. 

This computation procedure has been implemented by FORTRAN IV subroutine BLIPS, which is described and listed in Appendix G. This subroutine provides for designation of "solvent" components if not designated, they are determined internally. 

The computer subroutines for calculation of vapor-phase and liquid-phase fugacity (activity) coefficients, reference fugac-ities, and molar enthalpies, as well as vapor-liquid and liquid-liquid equilibrium ratios, are described and listed in this Appendix. These are source routines written in American National Standard FORTRAN (FORTRAN IV), ANSI X3.9-1978, and, as such, should be compatible with most computer systems with FORTRAN IV compilers. Approximate storage requirements and CDC 6400 execution times for these subroutines are given in Appendix J. 

The subroutines PARIN and PARCH are source routines written in American National Standard FORTRAN (FORTRAN IV), ANSI X3.9-1978, and should be compatible with most computer systems where input can be taken from logical unit 3. 

The programs DRFLA for vapor-liquid and DRELI for liquid-liquid calculations are written in FORTRAN IV source language for the CDC 6400 of the Computer Center, University of California, Berkeley. Minor modifications, mostly with regard to input and output, will be required for implementation on most other computer systems. 

The program storage requirements will depend somewhat on the computer and FORTRAN compiler involved. The execution times can be corrected approximately to those for other computer systems by use of factors based upon bench-mark programs representative of floating point manipulations. For example, execution times on a CDC 6600 would be less by a factor of roughly 4 than those given in the tcible and on a CDC 7600 less by a factor of roughly 24. 

This actually translates into a fairly simple algorithm, based closely on the standard velocity Verlet method. Written in a Fortran-like pseudo-code, it is as follows. At tire start of the run we calculate both rapidly-varying (1) and slowly-varying (F) forces, then, in the main loop ... 

A very pedagogical, highly readable introduction to quasi-Newton optimization methods. It includes a modular system of algoritlnns in pseudo-code which should be easy to translate to popular progrannning languages like C or Fortran. 

Thus At = n Ati = riin2St. It is simple matter to write down the Fortran pseudocode for this breakup. 

D. W. Noid, B. G. Sumpter, B. Wunderlich and G. A. Pfeffer, Molecular dynamics simulations of polymers Methods for optimal Fortran programming , J. Comput. Chem., 11(2), 236-241, 1990. 

An important though deman ding book. Topics include statistical mechanics, Monte Carlo sim illation s. et uilibrium and non -ec iiilibrium molecular dynamics, an aly sis of calculation al results, and applications of methods to problems in liquid dynamics. The authors also discuss and compare many algorithms used in force field simulations. Includes a microfiche containing dozens of Fortran-77 subroutines relevant to molecular dynamics and liquid simulations. 

Figures 5.4 and 5.8 Press W H, B P Flannery, S A Teukolsky and W T Vetterling, Numerical Recipes in Fortran. 1992, Cambridge University F ess.

MOBAS was written by the author (Rogers, 1983) in BASIC to illustrate matrix inversion in molecular orbital calculations. It is modeled after a program in FORTRAN n given by Dickson (Dickson, 1968). 

SHMO is a simple Huckel MO program in FORTRAN that functions much as MOBAS does and is also based on the Dickson program. The SHMO source code must be compiled. Compiled SHMO is in executable code (.exe). Run SHMO from the system level (do not go into BASIC) with the single command... 

Chirlian, P. M., 1981. Microsoft FORTRAN. Dilithium Press, Beaverton, OR. 

Souree - This folder (direetory) eontains all FORTRAN souree eode, inelude files, Makefiles, and the master eopy of the basis set library. 

In order to balance public domain science with a high quality commercial software product it has been necessary for us to reimplement almost every aspect of computational chemistry embodied in HyperChem. All HyperChem source code is written in C or C-t-t, specified, designed, and implemented by Hyper-Chem s developers. We have stood on the scientific shoulders of giants, but we have not used their FORTRAN code Thus, although we have had access to MOPAC and other public domain codes for testing and other purposes, HyperChem computes MINDO, MNDO, and AMI wave functions, for example, with HyperChem code, not MOPAC code. We have made the effort to implement modern chemical science in a modern software-engineered product. 

This big increase in speed has not been without cost. The everyday machine codes and high-level languages (Fortran, Pascal, C, etc.) used to control operations in a standard computer are inappropriate for parallel processing, which needs its own instruction set and has led to the development of special languages for use with the transputer. 

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