Elastic collisions of sulfur and hydrogen in their ground states at low temperatures and spectroscopic parameters of SH（X^2∏） radical

ThispaperconstructstheinteractionpotentialoftheSH(X2Π)radicalbyusingthecoupled-clustersinglesdoubles-approximate-triplestheorycombiningthecorrelation-consistentquintuplebasissetaugmentedwiththediffusefunctions,aug-cc-pV5Z,inthevalencerange.Employingthepotential,itaccuratelydeterminesthespectroscopicparameters.ThepresentDe,Re,ωe,ωeχe,αeandBevaluesareof3.7767eV,0.13424nm,2699.846cm?1,47.7055cm-1,0.2639cm-1and9.4414cm-1,respectively,whichareinexcellentagreementwiththoseobtainedfromthemeasurements.Atotalof19vibrationalstateshasbeenfoundwhenJ=0bysolvingtheradialSchrdingerequationofnuclearmotion.Thecompletevibrationallevels,classicalturningpoints,initialrotationandcentrifugaldistortionconstantswhenJ=0arereportedforthefirsttime,whichareingoodaccordwiththeexperimentalresults.Thetotalandvariouspartial-wavecrosssectionsarecomputedfortheelasticcollisionsofsulfurandhydrogenintheirgroundstatesatlowtemperatureswhentwoatomsapproacheachotheralongtheSH(X2Π)potentialenergycurve.Overtheimpactenergyrangefrom1.0×10-11to1.0×10-4a.u.,eightshaperesonanceshavebeenfoundinthetotalelasticcrosssections.Foreachshaperesonance,theresonantenergyisaccuratelycalculated.Carefulinvestigationshavepointedoutthattheseresonancesresultfromthel=0,1,2,3,4,6,7,8partial-wavecontributions.