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At least 19 records

Computer program for calculating and fitting thermodynamic functions

A computer program is described which (1) calculates thermodynamic functions (heat capacity, enthalpy, entropy, and free energy) for several optional forms of the partition function, (2) fits these functions to empirical equations by means of a least-squares fit, and (3) calculates, as a function of temperture, heats of formation and equilibrium constants. The program provides several methods for calculating ideal gas properties. For monatomic gases, three methods are given which differ in the technique used for truncating the partition function. For diatomic and polyatomic molecules, five methods are given which differ in the corrections to the rigid-rotator harmonic-oscillator approximation. A method for estimating thermodynamic functions for some species is also given.

Mcbride, Bonnie J.↗

CAP: A Computer Code for Generating Tabular Thermodynamic Functions from NASA Lewis Coefficients

For several decades the NASA Glenn Research Center has been providing a file of thermodynamic data for use in several computer programs. These data are in the form of least-squares coefficients that have been calculated from tabular thermodynamic data by means of the NASA Properties and Coefficients (PAC) program. The source thermodynamic data are obtained from the literature or from standard compilations. Most gas-phase thermodynamic functions are calculated by the authors from molecular constant data using ideal gas partition functions. The Coefficients and Properties (CAP) program described in this report permits the generation of tabulated thermodynamic functions from the NASA least-squares coefficients. CAP provides considerable flexibility in the output format, the number of temperatures to be tabulated, and the energy units of the calculated properties. This report provides a detailed description of input preparation, examples of input and output for several species, and a listing of all species in the current NASA Glenn thermodynamic data file.

Zehe, Michael J.↗

CAP: A Computer Code for Generating Tabular Thermodynamic Functions from NASA Lewis Coefficients

For several decades the NASA Glenn Research Center has been providing a file of thermodynamic data for use in several computer programs. These data are in the form of least-squares coefficients that have been calculated from tabular thermodynamic data by means of the NASA Properties and Coefficients (PAC) program. The source thermodynamic data are obtained from the literature or from standard compilations. Most gas-phase thermodynamic functions are calculated by the authors from molecular constant data using ideal gas partition functions. The Coefficients and Properties (CAP) program described in this report permits the generation of tabulated thermodynamic functions from the NASA least-squares coefficients. CAP provides considerable flexibility in the output format, the number of temperatures to be tabulated, and the energy units of the calculated properties. This report provides a detailed description of input preparation, examples of input and output for several species, and a listing of all species in the current NASA Glenn thermodynamic data file.

Zehe, Michael J.↗

Glass Transition Characteristics and Thermodynamic Functions of (1–x)(0.75TeO{sub 2}–0.25WO{sub 3}) + xLa{sub 2}O{sub 3} Glasses

The temperature-dependent heat capacity of three high-purity (1–x)(0.75TeO{sub 2}–0.25WO{sub 3}) + xLa{sub 2}O{sub 3} tellurite glass samples (x = 0.02, 0.04, and 0.06) has been determined by dynamic calorimetry in the range 320–1000 K. The experimental devitrification and heat capacity data have been used to evaluate standard thermodynamic functions: C{sub p}{sup o}(T), enthalpy, entropy, and Gibbs energy in glassy and supercooled liquid states. We have demonstrated model-parameter similarity of properties in a statistical approach and found correlation relationships for parameters as functions of composition, which make it possible to predict the thermodynamic functions of unexplored glasses of this series. We have identified crystallization-resistant compositions of (1–x)(0.75TeO{sub 2}–0.25WO{sub 3}) + xLa{sub 2}O{sub 3} glasses as a basis for the development of optically active elements.

36 MATERIALS SCIENCE↗

Temperature corrections to the thermodynamic functions of a degenerate neutron gas in a magnetic field

Temperature corrections to the basic thermodynamic functions calculated in our earlier publication for a degenerate neutron gas in a magnetic field are determined taking into account the anomalous magnetic moment of a neutron. The heat capacity and entropy of the degenerate neutron gas, as well as the temperature correction to the magnetic susceptibility, are also calculated. Additional arguments supporting the effect of an increase in the pulse frequency of pulsars mentioned in the previous publication are formulated; the results of that publication are refined.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

Thermodynamic Functions and Electrical Resistivity of Fluid Lead in the Metal–Nonmetal Transition Range

A dynamic method is used to measure the thermodynamic functions and the electrical resistivity of fluid lead for a wide range of specific volume and pressure. The measurements errors have been reduced to a level comparable to those of stationary methods. It is found that the transition of the fluid from the metallic state to a nonmetallic state occurs when its specific volume increases 2.7 times relative to the normal value. In each individual experiment the transition occurred at almost a constant pressure, and was detected by the change in sign of the isochoric temperature coefficient of resistance determined for the entire series of the experiments. In the pressure range of 0.6–5 GPa, the specific volume at which the metal–nonmetal transition occurs is found to be independent of pressure, and therefore, the transition line is close to an isochore. For the whole range of states of fluid lead investigated here, the speed of sound and the Grüneisen coefficient have been determined.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

Program Computes Thermodynamic Functions

PAC91 is latest in PAC (Properties and Coefficients) series. Two principal features are to provide means of (1) generating theoretical thermodynamic functions from molecular constants and (2) least-squares fitting of these functions to empirical equations. PAC91 written in FORTRAN 77 to be machine-independent.

Mcbride, Bonnie J.↗