Resultados obtidos por cálculos Dirac-Fock correlacionados de 4 componentes para o fluoreto do elemento E119 (Eka-Frâncio) com base estável e precisa, livre de prolapso variacional, são reportados neste trabalho. No nível CCSD(T), a distância de equilíbrio R e , frequência harmônica w e e energia de dissociação D e são 2,432 Å, 354,97 cm -1 e 116,92 kcal mol -1 , respectivamente. Também são reportados base livre de prolapso variacional de 4 componentes para o elemento 119, uma curva analítica de energia potencial precisa e o espectro vibracional a partir dos dados obtidos no nível CCSD(T). Nossos resultados sugerem que a molécula E119F deva ser menos iônica que seus fluoretos alcalinos homólogos mais leves, em contraste com o senso químico comum baseado nas propriedades periódicas -era de se esperar nesta molécula a ligação química mais iônica possível. Também encontramos que a correção do tipo modelo de carga para negligenciar as integrais do tipo SS resulta em erros insignificantes e acelera os cálculos cerca de 3 vezes no nível CCSD(T) e cerca de 4 vezes no nível DFT/B3LYP.Results obtained with correlated 4-component Dirac-Fock calculations for element E119 (ekafrancium) fluoride with stable and accurate basis set (prolapse-free) are reported in this work. At CCSD(T) level, the equilibrium distance R e , harmonic frequency w e and dissociation energy D e are 2.432 Å, 354.97 cm -1 and 116.92 kcal mol -1 , respectively. A 4-component prolapse free basis set for E119, an accurate analytical potential energy curve and vibrational spectra from CCSD(T) data are also reported. Our results suggest that E119F should be less ionic than lighter alkaline fluoride homologues, in contrast to the common chemical belief based on periodic trends -it would be expected in this molecule the most ionic bond possible. We also found that the charge model correction to neglect SS integrals leads to negligible errors and speed up calculations close to three times at CCSD(T) level and close to 4 times at DFT/B3LYP level.
Keywords: super heavy elements (SHE), 4-component relativistic molecular calculations, 4-component gaussian basis sets, relativistic effects in chemistry
IntroductionThe quest for super heavy nuclei began in 1940's with the synthesis of new elements with an atomic number greater than uranium, and the search for new elements was boosted with the prediction of an "island of stability" 1 for super heavy elements (SHE) with atomic numbers 114,120 and 126. [2][3][4] Some predictions estimate half-lives for isotopes with special combination of proton and neutron numbers as long as 10 8 years, as for 290 Sg 184 . 5,6 Recently, the production of the super heavy elements 112 through 118 using "hot" fusion reactions attained special chemical interest since the reported half-lives are in order of seconds, orders of magnitude longer than those of isotopes produced by "cold" fusion reactions. In addition to short half-lives, the drawback of low production rates also makes chemical experiments expensive, difficult and hard to perfo...
