CREST-CRCN Seminar

Quantum mechanics is the theory that describes the behavior of matter at the nano scale. Though routinely applied to the electrons in a molecular system, quantum theory is generally not applied to the atomic nuclei (except for very simple molecules), because such “exact quantum dynamics” (EQD) calculations are regarded to be too difficult. This is due to the “curse of dimensionality”: the computational (CPU) cost scales exponentially with system dimensionality. A decade ago, the speaker and this team introduced the first EQD method proven to defeat exponential scaling. Recently, they have developed the much simpler, momentum symmetrized phase space Gaussian basis that achieves the same goal. A “universal” and remarkably simple code has been written, which is dimensionally independent, and which also exploits massively parallel algorithms. The codes have been used to calculate tens of thousands of exact vibrational quantum states for real molecules such as methyleneimine, acetonitrile, and most recently, benzene. Through these calculations, the speaker will demonstrate how to perform EQD calculations for much larger and more complex systems than ever previously realized.