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A comparison of internal energy calculation methods for diatomic moleculesVarious methods of calculating the internal energy of diatomic molecules are studied. An accurate and efficient method for computing the eigenvalues of the vibrational Schroedinger equation for an arbitrary potential is developed. The method is based on a finite-element discretization using the cubic Lobatto element. A combination of spectrum slicing and the Laguerre algorithm is used to solve for the eigenvalues. A simple method to compute the quasi-bound states is presented. For N2 molecules, all vibrational-rotational states of eleven available electronic potentials are computed, and summed to obtain the exact internal energy function with temperature. The total computation required 314 seconds of CPU-time on NASA's Cray 2 computer. Various approximate models are discussed and compared with the exact numerical simulation. It is shown that the splitting of the macroscopic internal energy into separate electronic, rotational, and vibrational energies is not justified at high temperatures.
Document ID
19900035393
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Liu, Yen
(NASA Ames Research Center Moffett Field, CA, United States)
Shakib, Farzin
(NASA Ames Research Center Moffett Field, CA, United States)
Vinokur, Marcel
(Sterling Software Palo Alto, CA, United States)
Date Acquired
August 14, 2013
Publication Date
January 1, 1990
Subject Category
Atomic And Molecular Physics
Report/Patent Number
AIAA PAPER 90-0351
Accession Number
90A22448
Distribution Limits
Public
Copyright
Other

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