## Abstract

We present some approaches to the computation of ultra-fast laser pulses capable of selectively breaking molecular bonds. The calculations are based on a mixed quantum-classical description: The electrons are treated quantum mechanically (making use of time-dependent density-functional theory), whereas the nuclei are treated classically. The temporal shape of the pulses is tailored to maximize a control target functional which is designed to produce the desired molecular cleavage. The precise definition of this functional is a crucial ingredient: we explore expressions based on the forces, on the momenta and on the velocities of the nuclei. The algorithm used to find the optimum pulse is also relevant; we test both direct gradient-free algorithms, as well as schemes based on formal optimal control theory. The tests are performed both on one dimensional models of atomic chains, and on first-principles descriptions of molecules.

Original language | American English |
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Pages (from-to) | 50-61 |

Number of pages | 12 |

Journal | Chemical Physics |

Volume | 391 |

Issue number | 1 |

DOIs | |

State | Published - 24 Nov 2011 |

Externally published | Yes |

### Bibliographical note

Funding Information:This work was partially supported by the Deutsche Forschungsgemeinschaft within the SFB 658, and by the research project FIS2009-13364-C02-01 (MICINN, Spain).

## Keywords

- Quantum optimal control theory
- Time-dependent density-functional theory