The ab initio multiple spawning, or AIMS, method is a time-dependent
formulation
Formulation is a term used in various senses in various applications, both the material and the abstract or formal. Its fundamental meaning is the putting together of components in appropriate relationships or structures, according to a formul ...
of
quantum chemistry
Quantum chemistry, also called molecular quantum mechanics, is a branch of physical chemistry focused on the application of quantum mechanics to chemical systems, particularly towards the quantum-mechanical calculation of electronic contributions ...
.
In AIMS, nuclear dynamics and electronic structure problems are solved
simultaneously
Simultaneity may refer to:
* Relativity of simultaneity, a concept in special relativity.
* Simultaneity (music), more than one complete musical texture occurring at the same time, rather than in succession
* Simultaneity, a concept in Endogene ...
.
Quantum mechanical effects in the nuclear dynamics are included, especially the
nonadiabatic effects which are crucial in modeling dynamics on multiple electronic states.
The AIMS method makes it possible to describe
photochemistry from first principles molecular dynamics, with no empirical parameters. The method has been applied to two molecules of interest in organic photochemistry -
ethylene
Ethylene (IUPAC name: ethene) is a hydrocarbon which has the formula or . It is a colourless, flammable gas with a faint "sweet and musky" odour when pure. It is the simplest alkene (a hydrocarbon with carbon-carbon double bonds).
Ethylene i ...
and
cyclobutene.
The photodynamics of
ethylene
Ethylene (IUPAC name: ethene) is a hydrocarbon which has the formula or . It is a colourless, flammable gas with a faint "sweet and musky" odour when pure. It is the simplest alkene (a hydrocarbon with carbon-carbon double bonds).
Ethylene i ...
involves both
covalent and
ionic electronic excited states and the return to the ground state proceeds through a pyramidalized geometry. For the photoinduced ring opening of cyclobutene, is it shown that the disrotatory motion predicted by the
Woodward–Hoffmann rules is established within the first 50 fs after optical excitation.
The method was developed by chemistry professor
Todd Martinez
Todd or Todds may refer to:
Places
;Australia:
* Todd River, an ephemeral river
;United States:
* Todd Valley, California, also known as Todd, an unincorporated community
* Todd, Missouri, a ghost town
* Todd, North Carolina, an unincorporated ...
.
References
* Ab Initio Multiple Spawning: Photochemistry from First Principles Quantum Molecular Dynamics, M. Ben-Nun, Jason Quenneville, and Todd J. Martínez, ''J. Phys. Chem. A'' 104 (2000), #22, pp. 5161–5175. DO
10.1021/jp994174i
* Nonadiabatic molecular dynamics: Validation of the multiple spawning method for a multidimensional problem, M. Ben-Nun and Todd J. Martínez, ''Journal of Chemical Physics'' 108, #17 (May 1, 1998), pp. 7244–7257. DO
10.1063/1.476142
Quantum chemistry
Theoretical chemistry
{{quantum-chemistry-stub