Knowledge Bank

We have build an Hamiltonian which quantitatively reproduces the vibrational energy levels in $\mathrm{<mrow\; data-mjx-texclass="ORD">12</mrow>}C2H2$, up to the near-infrared, and possibly visible $ranges1$. It is based on the clustering of the vibrational levels induced by a defined set of anharmonic resonances, which allows to block-diagonalize the energy matrix. We have now inserted the terms adequate for predicting the rotational structure in each cluster, allowing to reproduce the anomalous distortion constants determined in various overtone and combination bands. In addition, the mean energy spacing between the vibrational levels has been studied within selected clusters for various J-values.