Ab initio structure and vibration-rotation dynamics of germylene, GeH₂

Accurate structure and potential energy surface of germylene, GeH₂ , in its ground electronic state $$ ¹ A₁ were determined from ab initio calculations using the coupled-cluster approach in conjunction with the correlation-consistent basis sets up to sextuple-zeta quality. The Born-Oppenheimer equilibrium structural parameters for the $$ ¹ A₁ state are estimated to be r_e (GeH) = 1.5793 Å and ∠_e (HGeH) = 91.19^∘ . The term value T_e for the lowest excited electronic state ã³ B₁ of GeH₂ is predicted to be 9140 cm^-1 . The vibration-rotation energy levels for the $$ ¹ A₁ state of the ⁷⁴ GeH₂ , ⁷⁴ GeD₂ , ⁷² GeH₂ , and ⁷⁰ GeH₂ isotopologues were determined using a variational approach and compared with the experimental data. The role of the core-electron correlation, higher-order valence-electron correlation, scalar relativistic, spin-orbit, and adiabatic effects for prediction of the structure and vibration-rotation dynamics of the GeH₂ molecule is discussed. © 2019 Wiley Periodicals, Inc.