Non-Markovian dissipation of molecular vibrational energy via multi-quantum processes

• Published in: Chemical physics letters Vol. 334; no. 1; pp. 179 - 186
• Main Authors: Mančal, Tomáš, May, Volkhard
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 02.02.2001; Elsevier Science
• Subjects: Atomic and molecular physics; Exact sciences and technology; Molecular properties and interactions with photons; Molecular spectra; Physics; Vibronic, rovibronic and rotation-electron-spin interactions; Polyatomic molecules; Numerical solution; Electronically excited state; Vibrational modes; Vibrational relaxation; Theoretical study; Multiquantum process; Analytical solution; Master equations
• ISSN: 0009-2614; 1873-4448
• DOI: 10.1016/S0009-2614(00)01416-0

In molecular systems where only a small set of active vibrational coordinates couples to electronic transitions a description by means of a reduced density operator becomes possible. For such systems it will be demonstrated that in the case of a nonlinear coupling between active and passive vibrational coordinates: (i) the passive-coordinate correlation function incorporates a time-independent part, and (ii) resulting from this, the standard Redfield theory which is of the Markovian type cannot be further applied. The respective non-Markovian dissipative dynamics are discussed for a simple model system, and in particular, the reasonableness of a time-independent correlation function is demonstrated. For cases where the constant part of the correlation function dominates, the related non-Markovian density matrix equation can be solved analytically and its solution is shown to be formed by two non-interfering wavepackets.