Regensburg 2004 – scientific programme
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CPP: Chemische Physik und Polymerphysik
CPP 16: POSTER: Computational Physics, Complex Systems
CPP 16.4: Poster
Tuesday, March 9, 2004, 17:00–19:00, B
Theoretical investigations of excited states of C3 — •Alexander Terentyev, Reinhard Scholz, and Michael Schreiber — Institut für Physik, Technische Universität Chemnitz
In this work, we present ab initio calculations for the potential energy surfaces of C3 in different electronic configurations, including the singlet ground state [X1Σg+, (1A1)], the triplet ground state [ã3Πu, (3B1, 3A1)], and some higher excited states. The geometries studied include triangular shapes with two identical bond length, but different bond angles between them. For the singlet and triplet ground states in the linear geometry, the total energies resulting from the B3LYP and QCISD approaches as implemented in the gaussian98 package reproduce the experimental values, i.e. the triplet occurs 2.1 eV above the singlet. In the geometry of an equilateral triangle, we find a low-lying triplet state with an energy of only 0.8 eV above the energy of the singlet in the linear configuration, so that the triangular geometry yields the lowest excited state of C3. For the higher excited states up to about 8 eV above the ground state, we apply time-dependent density functional theory (TD-DFT) based on the mixed B3LYP functional. Even though the systematic error produced by this approach is of the order of 0.4 eV, the results give new insight into the potential energy landscape for higher excitation energies.