Interaction of DNA base pairs with various metal cations (Mg2+, Ca2+, Sr2+, Ba2+, Cu+, Ag+, Au+, Zn2+, Cd2+, and Hg2+): nonempirical ab initio calculations on structures, energies, and nonadditivity of the interaction - Burda, J V; Šponer, J; Leszczynski, J; Hobza, P (J Phys Chem B, 1997)