- HCl initial level labelled from 2 to 20
- HCl final level labelled from 1 to 19
- H2 initial level labelled from 1 to 1
- H2 final level labelled from 1 to 1
- 8 temperatures between 10 K and 300 K
- Units : cm
^{3}s^{-1}

**HCl **

N/A

Reduced Mass = 1.9087 a.m.u.

The calculation of the PES assumes that both HCl and H

The HCl-H

The calculations were performed at 39 fixed distances in the range 3.5-50 a

- Green S.. Rotational excitation in H
_{2}-H_{2}collisions: close-coupling calculations J. Chem. Phys. vol62 : p2271--2277, 1975 - Boys S.~F., Bernardi F.. The calculation of small molecular interactions by the differences of separate total energies. Some procedures with reduced errors. Mol. Phys. vol19 : p553--566, 1970, October

Close-coupling (CC) calculations are performed for total energies E

Hyperfine cross sections are obtained through a recoupling technique, in a two step procedure. First, CC calculations are performed just taking into account the rotational energy levels of HCl, which leads to obtain the scatering matrix elements S

0.5 to 3000 cm

The number of HCl rotational states was adjusted to ensure convergence and include at least 5 closed rotational levels.

The j=0 and 2 para-H

For the current PES, the accuracy is better than 5% for inelastic rotational transitions within the j=0 state of para-H

The use of the recoupling technique to provide hyperfine rate coefficients introduces an additional error with respect to a full CC calculation. The accuracy of such a method is however expected to be high (of the order or better than 1%) given the small difference in energy between hyperfine levels (tens of 0.001 cm

Hyperfine de-excitation rate coefficients are provided among the first 6 rotational levels of HCl (up to j=5), for collisions with para-H_{2}(j=0) and for temperatures in the range 10-300K. Either the ^{35}Cl and ^{37}Cl nuclei have nuclear spins I=3/2 that split every rotational levels in 4 hyperfine levels for j>1. Rate coefficients thus consider a total of 20 hyperfine levels and apply to H^{35}Cl. The same set of rate coefficients can be used for the H^{37}Cl isotopologue: an additional error is however introduced (presumably of a few percents) due to the difference in reduced mass between the H^{35}Cl-H_{2} and H^{37}Cl-H_{2} systems.

- Lanza M., Lique F.. Hyperfine excitation of linear molecules by para- and ortho-H
_{2}: Application to the HCl-H_{2}system J. Chem. Phys. vol141 : 16 : p164321, 2014, October

Status |
Version |
Date |
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Collision added into the database | 1 | 2016-03-16 |