Nonadiabatic coupling in the Li2-Li2+ system

1985 ◽  
Vol 50 (5) ◽  
pp. 1010-1021
Author(s):  
Jan Vojtík ◽  
Alena Krtková ◽  
Rudolf Polák
Keyword(s):  
Potential Energy ◽  
Configuration Space ◽  
Potential Energy Surfaces ◽  
Nonadiabatic Coupling ◽  
Nonadiabatic Effects ◽  
Basic Characteristics ◽  
Chemical Conditions ◽  
Energy Surfaces

Nonadiabatic coupling between the lowest two doublet potential energy surfaces of the Li2-Li2+ system is calculated using the semiempirical VB technique of diatomics-in-molecules (DIM). Location of nonadiabatic region in the configuration space and basic characteristics of the system in nonadiabatic and asymptotic regions are used to discuss the influence of the nonadiabatic effects on the behaviour of the Li2-Li2+ system under chemical conditions.

Interpolating moving least-squares methods for fitting potential energy surfaces: Using classical trajectories to explore configuration space

2009 ◽  
Vol 130 (14) ◽  
pp. 144107 ◽  
Author(s):  
Richard Dawes ◽  
Alessio Passalacqua ◽  
Albert F. Wagner ◽  
Thomas D. Sewell ◽  
Michael Minkoff ◽  
...  
Keyword(s):  
Potential Energy ◽  
Least Squares ◽  
Configuration Space ◽  
Potential Energy Surfaces ◽  
Moving Least Squares ◽  
Classical Trajectories ◽  
Energy Surfaces

The intersection of potential energy surfaces in polyatomic molecules

1975 ◽  
Vol 344 (1637) ◽  
pp. 147-156 ◽  
Keyword(s):  
Wave Function ◽  
Potential Energy ◽  
Electronic State ◽  
Configuration Space ◽  
Potential Energy Surfaces ◽  
Polyatomic Molecules ◽  
The State ◽  
State Changes ◽  
Energy Surfaces ◽  
Recent Claim

It is proved that if the wave function of a given electronic state changes sign when transported adiabatically round a loop in nuclear configuration space, then the state must become degenerate with another one at some point within the loop. I t is further shown that this condition is satisfied by certain unsymmetrical triatomic systems, thereby disposing of a recent claim that the non-crossing rule for diatomic molecules applies also to polyatomic molecules.

An ab initio study of the potential energy surfaces for the collision between a Cs atom and an I2 molecule

2004 ◽  
Vol 82 (7) ◽  
pp. 1216-1222
Author(s):  
Xiaomin Sun ◽  
Dacheng Feng ◽  
Zhengting Cai ◽  
Wensheng Bian
Keyword(s):  
Potential Energy ◽  
Ab Initio ◽  
Cross Section ◽  
Potential Energy Surfaces ◽  
Ion Pair ◽  
Pair Formation ◽  
Nonadiabatic Coupling ◽  
Formation Cross Section ◽  
Ion Pair Formation ◽  
Energy Surfaces

For the Cs + I2 collision system, a systematic theoretical study is first reported using the ab initio method. Three of eight possible channels are considered. The nonadiabatic coupling between the covalent state and the ionic one is calculated from different angles, especially the T-shape collision. The complete ion-pair formation potential energy surfaces of the T-shape collision in two electronic states (ionic 2B2 state and covalent 2A1 state) and the reactive surface of the linear collision are constructed at the QCISD(T)/SDD level. The main features of potential energy surfaces, such as the minimum energy reaction path, the crossing radius (Rc), and energy minimum geometries, are analyzed. The cross section of this titled system is calculated based on the harpoon mechanism and compared with the available experimental data and those obtained for the M + I2 (M = Li, Na) systems.Key words: ab initio two-state potential energy surfaces, nonadiabatic coupling, ion-pair formation, cross section.

scholarly journals Dynamic signature of electronically nonadiabatic coupling in sodium hydride: a rigorous test for the symmetric quasi-classical model applied to realistic, ab initio electronic states.

2021 ◽  
Author(s):  
Justin J. Talbot ◽  
Martin Head-Gordon ◽  
William H. Miller ◽  
Stephen J. Cotton
Keyword(s):  
Population Dynamics ◽  
Potential Energy ◽  
Potential Energy Surfaces ◽  
Quantum Dynamics ◽  
Electronic States ◽  
Sodium Hydride ◽  
Quantum Mechanical ◽  
Population Transfer ◽  
Nonadiabatic Coupling ◽  
Energy Surfaces

Sodium hydride (NaH) in the gas phase presents a seemingly simple electronic structure making it a potentially tractable system for the detailed investigation of nonadiabatic molecular dynamics from both computational and experimental standpoints. The single vibrational degree of freedom, as well as the strong nonadiabatic coupling that arises from the excited electronic states taking on considerable ionic character, provides a realistic chemical system to test the accuracy of quasi-classical methods to model population dynamics where the results are directly comparable against quantum mechanical benchmarks. Using a simulated pump-probe experiment, this work presents computational predictions of population transfer through the avoided crossings of NaH via symmetric quasi-classical Meyer-Miller (SQC/MM), Ehrenfest, and exact quantum dynamics on realistic, ab initio potential energy surfaces. The main driving force for population transfer arises from a sharply localized avoided crossing between the C and D singlet sigma potential energy surfaces which causes most of the population to transfer between t=15 and t=30 fs depending on the initially excited vibronic wavepacket. While quantum mechanical effects are expected due to the reduced mass of NaH, predictions of the population dynamics from both the SQC/MM and Ehrenfest models perform remarkably well against the quantum dynamics benchmark. Additionally, an analysis of the vibronic structure in the nonadiabatically coupled regime and predicted transient absorption signatures are presented using a variational eigensolver methodology. The prospects for complementary experimental measurements are also assessed.

Spin-orbit coupling and the intersection of potential energy surfaces in polyatomic molecules

1976 ◽  
Vol 351 (1664) ◽  
pp. 141-150 ◽  
Keyword(s):  
Potential Energy ◽  
Configuration Space ◽  
Potential Energy Surfaces ◽  
Polyatomic Molecules ◽  
Orbit Coupling ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Lower Symmetry ◽  
Symmetry Species ◽  
Energy Surfaces

Longuet-Higgins’ theorem, which shows that the existence of intersections between potential energy surfaces may be deduced from the behaviour of the wavefunction at points remote from the intersection, is generalized to cover cases where the Hamiltonian is complex. It is concluded that an intersection due to symmetry in one region of nuclear configuration space may imply that the same surfaces intersect over a region of higher dimen­sion and lower symmetry where their wavefunctions belong to the same symmetry species. It is shown that this behaviour occurs in d 1 octahedral complexes in the presence of spin-orbit coupling.

Homology of Potential Energy Surfaces

1986 ◽  
Vol 41 (9) ◽  
pp. 1118-1122
Author(s):  
Ariel Fernández
Keyword(s):  
Potential Energy ◽  
Configuration Space ◽  
Potential Energy Surfaces ◽  
Transition States ◽  
Chemical Species ◽  
Basins Of Attraction ◽  
Intrinsic Reaction Coordinate ◽  
Sigmatropic Rearrangements ◽  
Stable Chemical ◽  
Energy Surfaces

It is shown that all the adjacency relations for the basins of attraction of stable chemical species and transition states can be derived from the topology of the pattern of intrinsic-reaction-coordinate- and-separatix trajectories in the nuclear configuration space.The results are applied to thermal [1,3] sigmatropic rearrangements and they show that even the symmetry-forbidden path proceeds concertedly. The corresponding homological formulas giving the adjacency relations are derived.

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