All Figures

$\begin{figure} \par\includegraphics[width=7.6cm,clip]{5718fig1} \end{figure}$ Figure 1: Contour plot of the analytical ground PES of the SiO-He system obtained from the present ab initio calculations, as a function of Jacobi coordinates R and $\theta$ . The SiO bond length is held fixed to $r_{\rm eq}=2.853$ bohr. Contours are drawn in steps of 1 cm^-1 with a maximum energy of 0 cm^-1.
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In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{5718fig2} \end{figure}$ Figure 2: Cuts of the analytical SiO-He PES at given values of the Jacobi angle. The ab initio PES obtained in the present work is compared to the PESs computed by Bieniek & Green (1981) (BK PES-FIT1) and by Sisak & Secrest (1991) (BK PES-FIT2).
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In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{5718fig3} \end{figure}$ Figure 3: Comparison of the first four $V_{\lambda }(R)$ radial terms associated with the SiO-He PESs obtained from the present ab initio calculations and the analytic fit (FIT2) of Sisak & Secrest (1991) to the energy points computed by Bieniek & Green (1981).
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In the text

$\begin{figure} \par\includegraphics[width=16.5cm,clip]{5718fig4} \end{figure}$ Figure 4: Rotational de-excitation and excitation cross sections ( upper and lower panel, respectively) of the SiO molecule in collision with He as a function of the relative kinetic energy. A logarithmic scale is used for both axes. Bold lines: odd $\Delta j=\vert j-j^{\prime }\vert$ inelastic transitions; thin lines: even $\Delta j=\vert j-j^{\prime }\vert$ inelastic transitions.
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In the text

$\begin{figure} \par\includegraphics[width=6.5cm,clip]{5718fig5} \end{figure}$ Figure 5: Rotational (de)excitation cross sections of the SiO molecule in collision with He for the $j=1\rightarrow j^{\prime }=0{-}4$ inelastic transitions at the total energy E=218.0 cm^-1. Results obtained from the present work and CC calculations of Sisak & Secrest (1992) using the PES of Bieniek & Green (1981).
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In the text

$\begin{figure} \par\includegraphics[width=15.5cm,clip]{5718fig6} \end{figure}$ Figure 6: Rotational de-excitation rate coefficients of the SiO molecule in collision with He. Upper-left panel: rate coefficients for SiO(j=6) as a function of $\Delta j=j-j^{\prime }$ for several temperatures; upper-right panel: rate coefficients for SiO(j=2-6) and T=100 K as a function of $\Delta j$ ; lower panel: rate coefficients for SiO(j=1-6) as a function of temperature for $\Delta j=1{-}3$ .
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In the text

$\begin{figure} \par\includegraphics[width=16.4cm,clip]{5718fig7} \end{figure}$ Figure 7: Estimated values of the rotational de-excitation rate coefficients of SiO(j) in collision with para-H₂(j=0) obtained from: CC scattering calculations using the SiO-H₂ reduced mass and the SiO-He ab initio PES (filled circles); SiO-He de-excitation rate coefficients corrected from the square root of the reduced mass ratio $\mu _{\rm SiO-He}/\mu _{\rm SiO-H_2}$ (dotted line); coupled-states scattering calculations of Turner et al. (1992) using the SiO-H₂ reduced mass and the SiO-He PES of Bieniek & Green (1981) (empty circles).
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In the text

$\begin{figure} \par\includegraphics[width=7.6cm,clip]{5718fig1} \end{figure}$	Figure 1: Contour plot of the analytical ground PES of the SiO-He system obtained from the present ab initio calculations, as a function of Jacobi coordinates R and $\theta$ . The SiO bond length is held fixed to $r_{\rm eq}=2.853$ bohr. Contours are drawn in steps of 1 cm^-1 with a maximum energy of 0 cm^-1.
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$\begin{figure} \par\includegraphics[width=8cm,clip]{5718fig2} \end{figure}$	Figure 2: Cuts of the analytical SiO-He PES at given values of the Jacobi angle. The ab initio PES obtained in the present work is compared to the PESs computed by Bieniek & Green (1981) (BK PES-FIT1) and by Sisak & Secrest (1991) (BK PES-FIT2).
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$\begin{figure} \par\includegraphics[width=8cm,clip]{5718fig3} \end{figure}$	Figure 3: Comparison of the first four $V_{\lambda }(R)$ radial terms associated with the SiO-He PESs obtained from the present ab initio calculations and the analytic fit (FIT2) of Sisak & Secrest (1991) to the energy points computed by Bieniek & Green (1981).
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$\begin{figure} \par\includegraphics[width=16.5cm,clip]{5718fig4} \end{figure}$	Figure 4: Rotational de-excitation and excitation cross sections ( upper and lower panel, respectively) of the SiO molecule in collision with He as a function of the relative kinetic energy. A logarithmic scale is used for both axes. Bold lines: odd $\Delta j=\vert j-j^{\prime }\vert$ inelastic transitions; thin lines: even $\Delta j=\vert j-j^{\prime }\vert$ inelastic transitions.
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$\begin{figure} \par\includegraphics[width=6.5cm,clip]{5718fig5} \end{figure}$	Figure 5: Rotational (de)excitation cross sections of the SiO molecule in collision with He for the $j=1\rightarrow j^{\prime }=0{-}4$ inelastic transitions at the total energy E=218.0 cm^-1. Results obtained from the present work and CC calculations of Sisak & Secrest (1992) using the PES of Bieniek & Green (1981).
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