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- Arteca, Gustavo A., et al.
(författare)
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Constructing quantum mechanical models from diabatic schemes : external field modulation of effective energy barriers for bond breaking/formation processes
- 2014
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Ingår i: Journal of Mathematical Chemistry. - : Springer Science and Business Media LLC. - 0259-9791 .- 1572-8897. ; 52:9, s. 2395-2410
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Tidskriftsartikel (refereegranskat)abstract
- We have recently proposed an approach where chemical transformations can be described as quantum processes involving the modulation of entangled states by an applied external field (Arteca and Tapia in Phys Rev A 84:012115, 2011). In practical implementations, we gain insight into these processes by using simple quantum-mechanical models derived from diabatic schemes. In this context, reactant, product, and, eventually, intermediate species, are assigned to diabatic basis functions, and then entangled by an external field into a quantum state from which all observable properties of the chemical reaction should emerge. Here, we extend our previous model for bond breaking/formation in diatomic molecules (Arteca et al. in J Math Chem 50:949, 2012). We consider the entire manifold of semiclassical models defined by only two diabatic basis functions: a harmonic well for the "molecular" bound state, and an exponential potential energy function for the asymptotically separated fragments (the "product" channel). Using a two-parameter space to describe all models, we determine how the topology of the total energy function is affected by the shape of the applied field. We show that strong and weak local couplings with the external field modify substantially the occurrence of energy barriers, in contrast to using the uniform (i.e., space-invariant) coupling employed in previous works.
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| 2. |
- Arteca, Gustavo A., et al.
(författare)
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Constructing quantum mechanical models starting from diabatic schemes : Quantum states for simulations bond break/formation-I. Feshbach-like quantum states and electronuclear wave functions
- 2012
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Ingår i: Journal of Mathematical Chemistry. - : Springer Science and Business Media LLC. - 0259-9791 .- 1572-8897. ; 50:4, s. 949-970
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Tidskriftsartikel (refereegranskat)abstract
- A quantum description adapted to scrutinize chemical reaction mechanisms obtains by implementing an electronuclear separation via quantum numbers method; truly diabatic base states obtain that sustain quantum states expressed as linear superpositions. A proto-type bond breaking/formation case: H-2(+) double left right arrow H(1s) + H+ test possibilities via mathematical modeling. Asymptotic states (vertical bar H > circle times vertical bar H+>) and (vertical bar H+> circle times vertical bar H >) and basis states for quantized electromagnetic radiation complete the model; Feshbach-resonance-like quantum states obtain that play pivotal roles gating association/dissociation processes. A fixed grid of floating Gaussian orbitals permits actual computations compatible with this method. The information therefrom gleaned is used to construct model Hamiltonians easily adaptable to second quantization formalisms. Theoretical developments and non-routine computations results can directly be related to experiment.
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