The ability to compute SCF and MP2 energies and forces at reduced cost makes dual-basis calculations
attractive for *ab initio* molecular dynamics simulations, which are described in Section 9.8.
Dual-basis BOMD has demonstrated^{Steele:2010a}
savings of 58%, even relative to state-of-the-art, Fock-extrapolated BOMD. Savings are further
increased to 71% for dual-basis RI-MP2 dynamics. Notably, these timings outperform estimates
of extended Lagrangian (“Car-Parrinello”) dynamics, without detrimental energy conservation
artifacts that are sometimes observed in the latter.^{Herbert:2004}

Two algorithm improvements make modest but worthwhile improvements to dual-basis dynamics. First,
the iterative, small-basis calculation can benefit from Fock matrix extrapolation.^{Herbert:2004}
Second, extrapolation of the response equations (“$Z$-vector” equations) for
nuclear forces further increases efficiency.^{Steele:2010b} (See Section 9.8.)
Q-Chem automatically
adjusts to extrapolate in the proper basis set when DUAL_BASIS_ENERGY is activated.