A geometry optimization benchmark using highly correlated wavefunctions (FCI and MRD-CI)

Full configuration interaction (FCI) geometry optimizations have been performed for the X(3)B(1), a(1)A(1), b(1)B(1) and c(1)A(1) electronic states of CH2, the X(2)B(1) and A(2)A(1) electronic states of NH2 and the X(1)A(1)' electronic state of BH3 using a DZP basis set. The results are compared with those obtained using the MRD-CI method at different levels of theoretical treatment. The agreement between the geometrical parameters optimized with the FCI and MRD-CI methods is very good.