SEARCH Articles Figures Tables Alternative Transformation for First-Order Energy Analysis of the first-order perturbation energy Contents 1 First-order Energy Surfaces Direct DKH Transformation of First-Order Energy Energy first Energy first-order effect Energy to first order First order self energy First-order correction to energy First-order electrostatic energy First-order energy correction First-order energy minimisation First-order perturbation energy Gibbs free energy first-order transitions Intermolecular perturbation first-order energy Operators first order reduced, factoring energy Ordering energy Potential energy first-order saddle point Potential energy surface first-order derivatives Potential-energy surfaces first order The Ground-State Energy to First-Order of Heliumlike Systems