Sri Laalitya Uppalapati

Calculating A Potential Energy Surface for the Rotational Excitation of NaK Molecules by He Atoms

Rotational energy transfer during inelastic collision between NaK molecules and He atoms was quantified both experimentally and theoretically, using quantum mechanical calculations. Experimental data shows a strong propensity for change in rotational quantum number (ΔJ) of NaK molecule to be even. Corresponding theoretical calculations require a potential energy surface for first excited state of NaK molecule (A1Σ+), followed by quantum mechanical coupled channel, scattering calculations.

Due to a NSF grant, I had the opportunity to work with Dr. A.P. Hickman at Lehigh University to develop an interpolation scheme to analytically map the potential energy surface of NaK-He system. The potential of A1Σ+ state can be broken up into three pair-wise interactions and a residual potential. Large fluctuations in the potential of NaK-He system were accounted for by the pair-wise interactions, so the residual potential was relatively smooth and easy to interpolate. A successful interpolation scheme was developed to circumvent the computer-time intensive calculation of potential energy surface using GAMESS code.