"On-the-fly" electronic structure calculations to be computed for quantum dynamics calculations present a major computational challenge. This is exacerbated when (a) multiple states need to be considered, or (b) the electronic structure is not simply represented using a single reference state. In this talk I will discuss a new technique to reduce the computational scaling in such problems. The features of the techniques are as follows: First, the computational scaling of the diabatic potential calculations on the nuclear coordinate space is reduced by tessellating (or partitioning) the space based on dynamical parameters such as wavepacket, previous approximations to the potential, its gradient and perhaps the Shannon entropy of the wavepacket. The tessellation reduces complexity substantially. Second, diabatic state surfaces and off-diagonal elements of CI-matrices constructed yield adiabatic surfaces for wavepacket dynamics. We will also note that the second step may not in general be necessary and the dyanmics is also shown to evolve on the coupled diabatic states directly. Finally, the diabatic surfaces can themselves be evolved as a function of time to further refine the dynamics. Time-dependent and time-independent studies on hydrogen-bonded systems are provided as illustrations. <br/>

Approximate time-dependent diabatic states computed using a measure driven tessallation technique for use in on-the-fly quantum dynamics methods

249th National Meeting (2015)

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