Space-time contours to treat intense field-dressed molecular states

• Published in: The Journal of chemical physics Vol. 132; no. 3; pp. 034303 - 034303-10
• Main Authors: Paul, Amit K., Adhikari, Satrajit, Baer, Michael
• Format: Journal Article
• Language: English
• Published: United States American Institute of Physics 21.01.2010
• Subjects: ACCURACY; APPROXIMATIONS; BORN-OPPENHEIMER APPROXIMATION; BOSONS; CALCULATION METHODS; CATIONS; CHARGED PARTICLES; CHEMICAL REACTIONS; COLLISIONS; DECOMPOSITION; DISSOCIATION; ELEMENTARY PARTICLES; HYDROGEN IONS; HYDROGEN IONS 2 PLUS; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; IONS; KINETICS; MASSLESS PARTICLES; MOLECULAR IONS; MOLECULE COLLISIONS; PHOTOCHEMICAL REACTIONS; PHOTOLYSIS; PHOTON COLLISIONS; PHOTON-MOLECULE COLLISIONS; PHOTONS; REACTION KINETICS; SPACE-TIME; TIME DEPENDENCE
• ISSN: 0021-9606; 1089-7690; 1089-7690
• DOI: 10.1063/1.3282333

In this article we consider a molecular system exposed to an intense short-pulsed external field. It is a continuation of a previous publication [ A. K. Paul , S. Adhikari , D. Mukhopadhyay , J. Phys. Chem. A 113 , 7331 ( 2009 ) ] in which a theory is presented that treats quantum effects due to nonclassical photon states (known also as Fock states). Since these states became recently a subject of intense experimental efforts we thought that they can be treated properly within the existing quantum formulation of dynamical processes. This was achieved by incorporating them in the Born-Oppenheimer (BO) treatment with time-dependent coefficients. The extension of the BO treatment to include the Fock states results in a formidable enhancement in numerical efforts expressed, in particular, in a significant increase in CPU time. In the present article we discuss an approach that yields an efficient and reliable approximation with only negligible losses in accuracy. The approximation is tested in detail for the dissociation process of H 2 + as caused by a laser field.