Quasistationary upper-well states of E×E Jahn–Teller systems with spin-orbit coupling

2007 ◽  
Vol 332 (2-3) ◽  
pp. 243-248 ◽  
Author(s):  
Leonid V. Poluyanov ◽  
Sabyashachi Mishra ◽  
Wolfgang Domcke
Keyword(s):  
Orbit Coupling ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Jahn Teller

The (E+A) × (e+a) Jahn–Teller and Pseudo-Jahn–Teller Hamiltonian Including Spin–Orbit Coupling for Trigonal Systems

2014 ◽  
Vol 118 (51) ◽  
pp. 11962-11970 ◽  
Author(s):  
Swarnendu Bhattacharyya ◽  
Daniel Opalka ◽  
Leonid V. Poluyanov ◽  
Wolfgang Domcke
Keyword(s):  
Orbit Coupling ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Jahn Teller

Buckling on stanene: the role played by spin-orbit coupling and pseudo Jahn-Teller effect

MRS Advances ◽  
2017 ◽  
Vol 2 (29) ◽  
pp. 1563-1569 ◽  
Author(s):  
J. R. Soto ◽  
B. Molina ◽  
J. J. Castro
Keyword(s):  
Dft Calculations ◽  
Group Iv ◽  
Vibronic Coupling ◽  
Coupling Constants ◽  
Orbit Coupling ◽  
Teller Effect ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Jahn Teller ◽  
Jahn Teller Effect

ABSTRACTTwo-dimensional group IV layers beyond graphene, as silicene, germanene and the Sn-based stanene, have been recently synthesized by molecular beam epitaxy. Density Functional Theyory (DFT) calculations predict low-buckled structures for these 2D nanosheets, with a hexagonal honeycomb conformation, typical of the graphene-like surfaces. The buckling parameter δ increases from Si to Sn-based layers, with a maximum predicted of 0.92 Å for stanene. High-buckled structures for these materials resulted to be unstable. We have previously shown that for silicene and germanene, the origin of the buckled structure resides on the pseudo Jahn-Teller puckering distortion, resulting from non-adiabatic effects. It has been shown that hexagermabenzene, the single hexagonal unit of germanene, is subject to a strong vibronic coupling whose origin is the pseudo Jahn-Teller effect. This coupling resulted to be around ten times larger than the one obtained for hexasilabenzene. For stanene, an additional effect needs to be considered to understand the origin of buckling: the spin-orbit coupling (SOC). This SOC contributes to open an electronic band gap, enabling the use of these layers as nanoelectronic components. In this work, we present an analysis based on DFT in the Zeroth-Order Regular Approximation (ZORA) for both scalar relativistic and spin-orbit versions that quantify the influence of the spin-orbit coupling in the puckering of Sn6H6. Also, under the linear vibronic coupling model between the ground and the lowest excited states, we present the pseudo Jahn-Teller contribution. The scalar ZORA approximation is used to perform time-dependent DFT calculations to incorporate the low-energy excitations contributions. Our model leads to the determination of the coupling constants and predicts simultaneously the Adiabatic Potential Energy Surface behavior for the ground and excited states around the maximum symmetry point. These values allow us to compare the Jahn-Teller relevance in buckling with the other group IV layers.

scholarly journals FIRST-PRINCIPLES SIMULATION OF THE CERIUM TRIFLUORIDE INFRARED SPECTRUM BEYOND THE BORN–OPPENHEIMER APPROXIMATION

2018 ◽  
Vol 61 (3) ◽  
pp. 31
Author(s):  
Oleg A. Vasilyev ◽  
Viktor G. Solomonik
Keyword(s):  
Dipole Moment ◽  
First Principles ◽  
Orbit Coupling ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Dipole Moment Operator ◽  
Cerium Trifluoride ◽  
Jahn Teller ◽  
Moment Operator ◽  
Oppenheimer Approximation

The group-theoretical analysis was carried out to derive a spin-vibronic model Hamiltonian and a diabatic dipole moment operator for a cerium trihalide molecule, CeX3. The model comprises seven lowest-lying 4f1 electronic states coupled by six vibrational modes, (A2'' + E' + E'' + A1' + A2') × (a1' + a2'' + e' + e'), with an accounting for spin-orbit coupling. Multimode potential energy surfaces have been calculated for the CeF3 molecule at the multi-reference singles and doubles configuration interaction level of theory corrected for quadruple excitations, MRCISD+Q, and dipole moment surfaces at the MRCISD level. A hybrid approach employing a quasi-diabatization technique was utilized to determine the relevant model parameters up to forth order in power series of the Q1(a1'), Q3(e'), Q4(e') normal coordinates, and eighth order of the Q2(a2'') out-of-plane bending normal coordinate. Spin-orbit coupling was taken into account through zero-order, with the respective constants obtained from matrix elements of the Breit–Pauli operator in the basis of states generated at the MRCISD level. The spin-vibronic Hamiltonian and dipole moment operator obtained in this way has been utilized in the variational calculations to simulate the infrared absorption spectrum of CeF3. The resulting spectrum features a complex structure owing to an intricate interplay of the vibronic (Jahn–Teller and pseudo-Jahn–Teller) and spin-orbit coupling effects, and hence cannot be explained within the conventional Born–Oppenheimer (BO) approximation. The strongest absorption appearing in the simulated spectrum at about 500 cm–1, mostly associated with the Q3(e') stretching mode, is split into two bands by about 3 cm–1. This finding is in full agreement with the CeF3 matrix isolation infrared spectroscopy data. On the whole, the results of the calculations clearly indicate the vibronic rather than vibrational origin of the spectral bands, including the bands in the low-frequency region of the spectrum, and thus show the fallacy of the generally accepted assignment of the bands observed in the experiment to the fundamental vibrational transitions of the molecule made on the assumption of the admissibility of describing this within the Born–Oppenheimer approximation. The new assignment of the experimental IR spectrum of CeF3 is proposed.Forcitation:Vasilyev O.A., Solomonik V.G. First-principles simulation of the cerium trifluoride infrared spectrum beyond the Born–Oppenheimer approximation. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 3. P. 31-44

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