title: On the unphysical impact of complex absorbing potentials on the Hamiltonian and its remedy.
abstract: The introduction of complex absorbing potentials as numerical tools to stabilize or increase the efficiency of calculations based on wave-packet propagation or on eigenvalue problems has the drawback of causing a modification of the Hamilton operator of the problem. In this work the consequences of such a modification are analyzed and the corrections required in order to properly describe the original physical process are derived. As an example, the decay of excited molecular states is considered: it is shown that the standard time-independent expression for the decay spectrum loses its validity when a complex absorbing potential is introduced in the nuclear Hamilton operator of the problem. To remedy the situation, a new, very stable formula is derived and tested on relevant model studies. Numerical examples are discussed.
authors.affiliation: Theoretische Chemie, Physikalisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 229, D-69120 Heidelberg, Germany. simona.scheit@tc.pci.uni-heidelberg.de
authors.forename: S
authors.initials: S
authors.lastname: Scheit
authors.forename: H-D
authors.initials: HD
authors.lastname: Meyer
authors.forename: N
authors.initials: N
authors.lastname: Moiseyev
authors.forename: L S
authors.initials: LS
authors.lastname: Cederbaum