34 KB352 KB31 KB199820252011Stare, Jernejštevilka:3letnik:58str. 501-508ISSN:1318-0207COBISSID:4834586URN:URN:NBN:SI:doc-MBQHFLMNenSlovenian Chemical SocietySlovensko kemijsko društvoActa chimica slovenicaanalizna kemijacoupled cluster calculationshidrogendifluoridni anionhydrogendifluoride anionmetoda sklopljenih skupkovpotential energy surfaceshort hydrogen bondingthree-dimensional fittingvibrational dynamicsvodikova vezA highly accurate, analytic potential energy surface of the hydrogendifluoride anion in the gas phase|We calculated the full three-dimensional potential energy surface (PES) of an isolated hydrogendifluoride anion (FHF-) in the electronic ground state at a very accurate Coupled Cluster approach and large correlation-consistent valence triple-zeta basis set CCSD(T)/aug-cc-pVTZ. The PES was evaluated at more than 30.000 points corresponding to different geometries of the system. Analytical form of the PES was expressed in an internal coordinate set which included the F...F separation (internal coordinate R) and the longitudinal and transversal projection (internal coordinates x and y) of the proton position on the F...F line. For each constant value of x a two-dimensional fit along y and R was performed by using displaced Gaussian functions. The fitted parameters of Gaussians were then spline-interpolated along x to get the final analytical form of the three-dimensional PES. The maximum fitting error was less than 0.01 kcal/mol in the lowest 20 kcal/mol region of the PES, yielding an accurate and conveniently formulated surface which can be readily used for advanced calculations, including fully coupled anharmonic vibrational analysis and quantum dynamics simulationZ zelo zanesljivim kvantno kemijskim pristopom (metoda sklopljenih skupkov, angl. Coupled Cluster) in velikim baznim setom smo izračunali polno, tridimenzionalno potencialno ploskev izoliranega hidrogendifluoridnega aniona (FHF-) v osnovnem elektronskem stanju račun CCSD(T)/aug-cc-pVTZ. Vrednosti potenciala smo ocenili v več kot 30.000 točkah, ki ustrezajo različnim geometrijam sistema. Analitično obliko potenciala smo zasnovali v internih koordinatah, in sicer razdalji F...F (koordinata R) ter longitudinalni in transverzalni projekciji položaja protona na zveznico F...F (koordinati x in y). Za vsako konstantno vrednost koordinate x smo napravili analitično prilagajanje vzdolž koordinat y in R, pri čemer smo uporabili linearno kombinacijo dvodimenzionalnih Gaussovih funkcij. Prilagojene parametre Gaussovih funkcij smo nato z metodo kubičnih zlepkov interpolirali vzdolž koordinate x. Največje odstopanje modelne funkcije od izračunanega potenciala znaša v območju nizke energije (do 20 kcal/mol nad minimumom) le 0.01 kcal/mol. Analitična oblika potenciala je zelo natančna in primerna za napredne računske študije kot npr. polno anharmonsko vibracijsko analizo ali kvandnodinamsko simulacijoTEXTznanstveno časopisjejournalsSlovenian National E-content AggregatorNational and University Library of SloveniaSlovensko kemijsko društvo