  We propose the use of parameter-free preentanglers as initial states for
quantum algorithms. We apply this idea to the electronic structure problem,
combining a quantized version of the Canonical Transformation by Yanai and Chan
[J. Chem. Phys. 124, 194106 (2006)] with the Complete Active Space Density
Matrix Renormalization Group. This new ansatz allows to shift the computational
burden between the quantum and the classical processor. In the vicinity of
multi-reference points in the potential energy surfaces of H$_2$O, N$_2$,
BeH$_2$ and the P4 system, we find this strategy to require significantly less
parameters than corresponding generalized unitary coupled cluster circuits. We
propose a new algorithm to prepare Matrix Product States based on the Linear
Combination of Unitaries and compare it to the Sequential Unitary Algorithm
proposed by Ran in [Phys. Rev. A 101, 032310 (2020)].
