HADRONICALLY-CORRELATED-SCF TREATMENT OF Li_4, A TEST CASE FOR CORRELATED ENERGY OF METAL CLUSTERS

摘要

Interest in Lit as a binary logic device with a magnetic triplet state and a diamagnetic singlet ground state provides a test case to compare "Hadronic Correlation" to previous work. Here the Coulomb interaction between electrons is modified to permit short-range attraction: f(r) = (1 - 2exp(-ar~2))/ r, instead of(1/r). The parameter "a" is fitted to give the quantum Monte Carlo energy of the HF molecule and is then treated as a variational parameter for the total energy of other molecules. This method provides near-experimental energies for CH_4, NH_3, H_2O and HF in short run times only about three times longer than Hartree Fock Roothaan basis SCF calculations. The best energy of Li_4 is ―29.9622099597 hartrees using the hadronically-correlated-SCF (hcscf) method. The energy of the optimized quasi-tetrahedral triplet state is ―29.94319370 hartrees using an 84-configuration interaction to express the open shell case; predicting an energy difference of 0.5174 ev (2396 nm or 4173/cm) between optimized triplet and singlet geometries.