Full configuration interaction (CI) provides the exact solution of the Schrodinger equation within a given basis set. However, due to its exponentially-growing computational cost, it can be applied only to small systems. In order to approach full CI energies, a determinant selection scheme based on propagator theory is reported. By propagating the imaginary-time Schrodinger equation in determinant space, significant determinants and corresponding coefficients are gradually included and optimized. In this way, the configuration interaction wavefunction is iteratively constructed and converged. The performance of our method is benchmarked against full CI results for Ne, C2, H2O, N2. Chemical accuracy energies are generally achieved with spawning threshold value about 1×104 to 1×105 and a 1×106 spawning threshold usually provides energies with an error of the order of 0.01 mEh.

Propagator based adaptive configuration interaction method

251st National Meeting (2016)

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