Asymptotic Expansion of the Partition Function of the Asymmetric Top

1951 ◽  
Vol 19 (9) ◽  
pp. 1131-1133 ◽  
Author(s):  
Kenneth F. Stripp ◽  
John G. Kirkwood
Keyword(s):  
Asymptotic Expansion ◽  
Partition Function ◽  
Asymmetric Top

On the effect of centrifugal stretching on the rotational partition function of an asymmetric top

1991 ◽  
Vol 95 (11) ◽  
pp. 8374-8389 ◽  
Author(s):  
J. M. L. Martin ◽  
J. P. François ◽  
R. Gijbels
Keyword(s):  
Partition Function ◽  
Asymmetric Top

scholarly journals Impact of nonconvergence and various approximations of the partition function on the molecular column densities in the interstellar medium

2019 ◽  
Vol 627 ◽  
pp. A65 ◽  
Author(s):  
M. Carvajal ◽  
C. Favre ◽  
I. Kleiner ◽  
C. Ceccarelli ◽  
E. A. Bergin ◽  
...  
Keyword(s):  
Partition Function ◽  
Column Density ◽  
Methyl Formate ◽  
Isocyanic Acid ◽  
Methyl Cyanide ◽  
Asymmetric Top ◽  
Function Approximations ◽  
Relative Differences ◽  
Internal Rotor ◽  
Typical Temperature

We emphasize that the completeness of the partition function, that is, the use of a converged partition function at the typical temperature range of the survey, is very important to decrease the uncertainty on this quantity and thus to derive reliable interstellar molecular densities. In that context, we show how the use of different approximations for the rovibrational partition function together with some interpolation and/or extrapolation procedures may affect the estimate of the interstellar molecular column density. For that purpose, we apply the partition function calculations to astronomical observations performed with the IRAM-30 m telescope towards the NGC 7538–IRS1 source of two N-bearing molecules: isocyanic acid (HNCO, a quasilinear molecule) and methyl cyanide (CH3CN, a symmetric top molecule). The case of methyl formate (HCOOCH3), which is an asymmetric top O-bearing molecule containing an internal rotor is also discussed. Our analysis shows that the use of different partition function approximations leads to relative differences in the resulting column densities in the range 9–43%. Thus, we expect this work to be relevant for surveys of sources with temperatures higher than 300 K and to observations in the infrared.

The rotational specific heat of a polyatomic molecule for high temperatures—correction

1933 ◽  
Vol 29 (3) ◽  
pp. 407-407 ◽  
Author(s):  
Irene E. Viney
Keyword(s):  
Asymptotic Expansion ◽  
Partition Function ◽  
Specific Heat ◽  
High Temperatures ◽  
Polyatomic Molecule ◽  
Department Of Commerce ◽  
Image Position

I am indebted to Mr L. Kassel of the Department of Commerce, U.S.A., for pointing out an error of computation in a recent paper in these Proceedings.The asymptotic expansion for the partition function should readwhere

Sign in / Sign up

Export Citation Format

Share Document