Development of Real-Time Projected Density Matrix Embedding Theory for the Application to Spin Dynamics

Accurate computational simulations of spin dynamics provide insight into behaviors of molecular and material systems, leading to informed advances in areas such as qubit stability in quantum computing. However, modeling unique spin states usually requires computationally expensive simulations, limiting the sizes of the systems and phenomena that can be studied. We are developing a method, real-time projected density matrix embedding theory (RT-pDMET), that simulates spin phenomena while balancing computational cost and accuracy via a quantum embedding algorithm. RT-pDMET simulates spin dynamics in the spin-generalized formalism, which is generalized by using mixed rather than pure spin up and down orbitals. Initial results show that RT-pDMET can accurately simulate both electron and spin dynamics in model Hamiltonians. We are also incorporating MPI parallelization to take advantage of the parallelizable nature of the algorithm, allowing RT-pDMET to be applied to model systems composed of hundreds of sites. A RT-pDMET in the spinor formalism will simulate dynamics involving complicated spin states under nonequilibrium conditions in larger systems than previously possible with ab initio methods, with wide-reaching applications in chemistry, physics, and materials science.