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Quantum simulations of electronic structure with a transformed Hamiltonian that includes some electron correlation effects are demonstrated. The transcorrelated Hamiltonian used in this work is efficiently constructed classically, at polynomial cost, by an approximate similarity transformation with an explicitly correlated two-body unitary operator. This Hamiltonian is Hermitian, includes no more than two-particle interactions, and is free of electron–electron singularities. We investigate the effect of such a transformed Hamiltonian on the accuracy and computational cost of quantum simulations by focusing on a widely used solver for the Schrödinger equation, namely the variational quantum eigensolver method, based on the unitary coupled cluster with singles and doubles (q-UCCSD) Ansatz. Nevertheless, the formalism presented here translates straightforwardly to other quantum algorithms for chemistry. Our results demonstrate that a transcorrelated Hamiltonian, paired with extremely compact bases, produces explicitly correlated energies comparable to those from much larger bases. For the chemical species studied here, explicitly correlated energies based on an underlying 6-31G basis had cc-pVTZ quality. The use of the very compact transcorrelated Hamiltonian reduces the number of CNOT gates required to achieve cc-pVTZ quality by up to two orders of magnitude, and the number of qubits by a factor of three. 

A hydrophilic ligand that contains only C, H, O, and N substituents and uses a 6,6′-bis(1H-1,2,3-triazol-4-yl)-2,2′-bipyridine (BTzBP) structural core has been synthesized. The effect of adding water-soluble groups onto extractant ligands has been extensively studied to facilitate the efficient partitioning of 4f and transuranic 5f elements for the treatment of spent nuclear fuel. Soft, N-donor ligands exhibit greater binding affinities for the trivalent actinides over the trivalent lanthanides, making BTzBP ligands an ideal candidate in the search for extractants to be used on an industrial scale. To date, hydrophobic BTzBPs have been shown to exhibit physical and chemical properties that might be conducive to nuclear waste processing conditions. However, hydrophilic BTzBPs have yet to be reported. Herein, we show the synthesis of a hydrophilic BTzBP ligand featuring cationic water solubilizing groups attached to the bipyridal rings.