The two main models for quantum computation are the (a) digital or gate based model and the (b) analog or adiabatic quantum computation approach. The later involves preparing an easy to prepare initial Hamiltonian. Then, the Hamiltonian parameters are slowly varied so as to drive the system to some target Hamiltonian. If the change is performed sufficiently slowly, the adiabatic theorem says the state of the system will remain an eigenstate throughout the evolution and adiabatically follow the changing Hamiltonian. Recently, VQAs and adiabatic state preparation have been combined enabling potentially more accurate simulations of quantum chemistry and related applications.