Using quantum dynamics simulations to follow the competition between charge migration and charge transfer in polyatomic molecules

Spinlove, K. Eryn; Vacher, Morgane; Bearpark, Michael J.; Robb, Michael A.; Worth, Graham A.

doi:10.1016/j.chemphys.2016.10.007

Cited by 17 publications

(9 citation statements)

References 45 publications

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“…The test system to be used to demonstrate the new implementations in the DD-vMCG code is theX state of the allene radical cation. This is a molecule that has been previously studied using a vibronic model Hamiltonian [52] and the nature of the coupling between the components of the degenerate state is known, making it an ideal target for the present study as a comparison of the results can support the accuracy of the method. It is also of a sufficient size to be a challenge for direct dynamics simulations, and has the added difficulty of having a conical intersection directly at the Frank-Condon point which can cause problems for simulations by introducing a strong non-adiabatic coupling from the start.…”

Section: F Allene Radical Cationmentioning

confidence: 99%

Improved algorithm for the direct dynamics variational multi-configurational Gaussian method

Christopoulou

Freibert

Worth

2021

The Journal of Chemical Physics

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The Direct Dynamics variational Multi-Configurational Gaussian (DD-vMCG) methods provides a fully quantum mechanical solution to the time-dependent Schrödinger equation for the time evolution of nuclei with potential surfaces calculated on-the-fly using a quantum chemistry program. Initial studies have shown its potential for flexible and accurate simulations of non-adiabatic excitedstate molecular dynamics. In this paper we present developments to the DD-vMCG algorithm that improve both its accuracy and efficiency. Firstly, a new, efficient parallel algorithm to control the DD-vMCG database of quantum chemistry points is presented along with improvements to the Shepard interpolation scheme. Secondly, the use of symmetry in describing the potential surfaces is introduced along with a new phase convention in the propagation diabatisation. Benchmark calculations on the allene radical cation including all degrees of freedom then show that the new scheme is able to produce a consistent non-adiabatic coupling vector-field. This new DD-vMCG version thus opens the route for effectively and accurately treating complex chemical systems using quantum dynamics simulations.

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Section: F Allene Radical Cationmentioning

confidence: 99%

Improved algorithm for the direct dynamics variational multi-configurational Gaussian method

Christopoulou

Freibert

Worth

2021

The Journal of Chemical Physics

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“…If the coupling between GWPs in the vMCG method is ignored, then the basis functions follow classical trajectories. clMCG is computationally faster and numerically more stable than vMCG, but has much slower convergence on the full quantum mechanical result and is dependent on the initial conditions chosen for a calculation [50].…”

Section: The Time-dependent Schrödinger Equationmentioning

confidence: 99%

“…In the simplest variant of the method, the evolving wavefunction is represented by a superposition of functions and the initial weights of the GWPs are kept fixed. The independent multi-configurational Gaussian method is thus equivalent to solving the TDSE with a swarm of classical trajectories [50].…”

Section: The Time-dependent Schrödinger Equationmentioning

confidence: 99%

Quantics: A general purpose package for Quantum molecular dynamics simulations

Worth

2020

Computer Physics Communications

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Quantics is a general purpose program package to simulate the time-evolution of a molecular system by solving the time-dependent Schrödinger Equation The main code is based on the multi-configurational time-dependent Hartree (MCTDH) algorithm in various variants, including the powerful multilayer-MCTDH algorithm that has been used to propagate a wavefunction for up to 1000 degrees of freedom. MCTDH uses a contraction of traditional discrete basis set representations of the Hamiltonian and wavefunction, and Quantics includes a range of variable representation (DVR) grid basis sets and collocation methods. Input is via ascii text files and for molecules with analytical potential functions no programming is required. A library of potential functions is included to treat more complicated cases, and this can be added to by the user. The code also includes the variational multi-configurational Gaussian (vMCG) method that is based on a Gaussian Wavepacket expansion of the wavefunction. vMCG can be run in a "direct" manner (DD-vMCG), calculating the potential energy surfaces on-the-fly using a number of quantum chemistry programs. In addition to wavepacket propagation, Quantics can solve the time-independent Schrödinger equation for small systems and can solve the Liouville-von-Neumann equation to propagate density matrices. The Package includes auxiliary programs to help set up calculations and analyse the output. Quantics is a community code of the UK Collaborative Computational Project for Quantum Dynamics (CCPQ) and the European E-CAM project, an e-infrastructure for software development run by the Centre Européen de Calcul Atomique et Moléculaire (CECAM). Through this it has become a framework for general dynamics codes, for example enabling * Corresponding author.

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“…Recent simulations are mostly devoted to isomerization, fragmentation or charge transfer in organic chromophores. [28][29][30] Simulations of quantum dynamics including dissociative coordinates 31 are still scarce and only one example has been reported for a 1 st -row transition metal complex, namely the ultrafast photolysis of the heme-CO complex. 32 The present study is devoted to quantum dynamics simulations capable to follow the competition between fluorescence and carbonyl loss in [Mn(im)(CO)3(phen)] + , in particular the axial carbonyl, see Scheme 1.…”

Section: Introductionmentioning

confidence: 99%

Excited-state dynamics of [Mn(im)(CO)3(phen)]+: PhotoCORM, catalyst, luminescent probe?

Fumanal

Daniel

Gindensperger

2021

The Journal of Chemical Physics

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Mn(I) -diimine carbonyl complexes have shown promise in the development of luminescent CO release materials (photoCORM) for diagnostic and medical applications due to their ability to balance the energy of the low-lying metal-to-ligand charge transfer (MLCT) and metalcentered (MC) states. In this work, the excited state dynamics of [Mn(im)(CO)3(phen)] + (im = imidazole; phen = 1,10-phenanthroline) is investigated by means of wavepacket propagation on the potential energy surfaces associated to the eleven low-lying Sn singlet excited states within a vibronic coupling model in a (quasi) diabatic representation including sixteen nuclear degrees of freedom. The results show that the early time photophysics (< 400 fs) is controlled by the interaction between two MC dissociative states, namely S5 and S11, with the lowest S1-S3 MLCT bound states. In particular, the presence of S1/S5 and S2/S11 crossings within the diabatic picture along the Mn-COaxial dissociative coordinate (qMn-COaxial) favours a twostepwise population of the dissociative states, at about 60-70 fs (S11) and 160-180 fs (S5), that reaches about 10% within 200 fs. The one-dimensional reduced densities associated to the dissociative states along qMn-COaxial as function of time clearly point to concurrent primary processes, namely CO release vs. entrapping into the S1 and S2 potential wells of the lowest luminescent MLCT states within 400 fs, characteristics of luminescent photoCORM.

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Using quantum dynamics simulations to follow the competition between charge migration and charge transfer in polyatomic molecules

Cited by 17 publications

References 45 publications

Improved algorithm for the direct dynamics variational multi-configurational Gaussian method

Improved algorithm for the direct dynamics variational multi-configurational Gaussian method

Quantics: A general purpose package for Quantum molecular dynamics simulations

Excited-state dynamics of [Mn(im)(CO)3(phen)]+: PhotoCORM, catalyst, luminescent probe?

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