Ignacio R. Solá, Vladimir S. Malinovsky
We show that a counter-intuitive pulse sequence leads to adiabatic passage between the vibrational levels of three harmonic potentials through parallel dark states in adiabatic approximation. However, the adiabatic assumptions break down for very intense pulses and non-adiabatic couplings result in the population transfer by light-induced potential shaping.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
继续探索
In this thesis I generalize Ring Polymer Molecular Dynamics (RPMD) rate theory to electronically non-adiabatic systems, followed by application to two one-dimensional curve crossing models and a multidimensional spin-boson model.
A software package, called DFTBaby, is published, which provides the electronic structure needed for running non-adiabatic molecular dynamics simulations at the level of charge-consistent tight-binding DFT. A long-range correction is incorporated to avoid spurious charge transfer states. Excited state energies, their analytic gradients and scalar non-adiabatic couplings are computed using tight-binding TD-DFT. These quantities are fed into a molecular dynamics code, which integrates Newton's equations of motion for the nuclei together with the electronic Schrödinger equation. Non-adiabatic eff…
A novel non-adiabatic spin relaxation mechanism in molecular qubits
本文提出含非绝热自旋-振动轨道相互作用的扩展分子自旋哈密顿量，建立双声子拉曼过程自旋弛豫模型，在Cu(II)卟啉上验证了高温弛豫由非绝热相互作用主导，结果与实验吻合。
State-selective molecular orientation by vibrational Autler-Townes adiabatic passage
提出全光Autler-Townes态选择性绝热通道，将分子制备到单一$|J,M\ angle$子能级，在$^{13}$CO$_2$中验证分裂并预测转移效率接近90%，可扩展至多种分子。
Charge transfer in collisions of Na_n^+ cluster ions with Cs atoms is investigated theoretically in the microscopic framework of non-adiabatic quantum molecular dynamics. The competing reaction channels and related processes affecting the charge transfer (electronic excitations, fragmentation, temperature) are described. Absolute charge transfer cross sections for Na_n^+(2.7 keV) + Cs --> Na_n + Cs^+ have been calculated in the size range 4 <= n <= 11 reproducing the size dependence of the experimental cross sections. The energy dependence of the cross section is predicted for n=4,7,9. An exot…
General transformation expressions of the second-order non-adiabatic Hamiltonian of the atomic nuclei, including the kinetic-energy correction terms, are derived upon the change from laboratory-fixed Cartesian coordinates to general curvilinear coordinate systems commonly used in rovibrational computations. The kinetic-energy or so-called "mass-correction" tensor elements are computed with the stochastic variational method and floating explicitly correlated Gaussian functions for the H$_2^+$ molecular ion in its ground electronic state. (Further numerical applications for the $^4$He$_2^+$ mole…
Accurate simulation of the non-adiabatic dynamics of molecules in excited electronic states is key to understanding molecular photo-physical processes. Here we present a novel method, based on a semiclassical approximation, that is as efficient as the commonly used mean field Ehrenfest or ad hoc Surface Hopping methods and properly accounts for interference and decoherence effects. This novel method is an extension of Hellers Thawed Gaussian wavepacket dynamics that includes coupling between potential energy surfaces. The accuracy of the method can be systematically improved.
The coupling of electronic and vibrational motion is studied by two canonical transformations namely normal coordinate transformation and momentum transformation on molecular Hamiltonian. It is shown that by these transformations we can pass from crude approximation to adiabatic approximation and then to non-adiabatic (diabatic) Hamiltonian. This leads to renormalized fermions and renormalized diabatic phonons. Simple calculations on $H_{2}$, $HD$, and $D_{2}$ systems are performed and compared with previous approaches. Problem of electronic quasi-degeneracy is discussed.
Topological Quantum Molecular Dynamics
本文提出统一量子几何框架与无散度的拓扑量子分子动力学方法，通过全局电子重叠矩阵编码奇异量子几何张量，证明绝热和非绝热原子运动同时受势能面与电子态几何变化支配。
The quantum dynamics of linear molecular aggregates in the presence of S0-S1 and S0-S2 transitions is investigated putting emphasis on the interplay between local non-adiabatic S2 to S1 deactivation and Frenkel exciton transfer. The theoretical approach combines aspects of the linear vibronic coupling and Frenkel exciton models. Dynamics calculations are performed for the absorption spectrum and the electronic state populations using the multiconfiguration time-dependent Hartree approach. As an application perylene bisimde J-type dimer and trimer aggregates are considered, including four tunin…
Collective two-color photoassociation of a freely-interacting 87Rb Bose-Einstein condensate is theoretically examined, focusing on stimulated Raman adiabatic passage (STIRAP) from an atomic to a stable molecular condensate. In particular, Drummond et al. [Phys. Rev. A 65, 063619 (2002); cond-mat/0110578] have predicted that particle-particle interactions can limit the efficiency of collective atom-molecule STIRAP, and that optimizing the laser parameters can partially overcome this limitation. We suggest that the molecular conversion efficiency can be further improved by treating the initial c…
The efficiencies of light-harvesting complexes in biological systems can be much higher than the current efficiencies of artificial solar cells. In this paper, we therefore propose and analyse an energy transport mechanism which employs adiabatic passages between the states of an artificially designed antenna molecular system to significantly enhance the conversion of incoming light into internal energy. It is shown that the proposed transport mechanism is relatively robust against spontaneous emission and de-phasing, while also being able to take advantage of collective effects. Our aim is to…
A semiclassical non-adiabatic phase-space approach to molecular translations and rotations: A new picture of surface hopping and electronic inertial effects
本文提出超越玻恩-奥本海默近似的半经典相空间表面跳跃方法，通过正确相空间电子哈密顿量捕捉电子惯性效应并消除非绝热跃迁，为手性声子-电子角动量转移和手性诱导自旋选择性研究开辟新途径。
We present a theoretical study of recent laser-alignment and mixed-field-orientation experiments of asymmetric top molecules. In these experiments, pendular states were created using linearly polarized strong ac electric fields from pulsed lasers in combination with weak electrostatic fields. We compare the outcome of our calculations with experimental results obtained for the prototypical large molecule benzonitrile (C$_7$H$_5$N) [J.L. Hansen et al, Phys. Rev. A, 83, 023406 (2011)] and explore the directional properties of the molecular ensemble for several field configurations, i.e., for var…
We examine collective magnetoassociation of a Bose-Einstein condensate (BEC), focusing on rapid adiabatic passage from atoms to molecules induced by a sweep of the magnetic field across a wide (>~ 10 G) Feshbach resonance in 85Rb. This problem raises an interest because strong magnetoassociation is expected to favor the creation of molecular-dissociated atom pairs over the formation of molecular BEC [Javanainen and Mackie, Phys. Rev. Lett. 88, 090403 (2002)]. Nevertheless, the conversion to atom pairs is found to depend on the direction of the sweep, so that a system initially above threshold …
The mass-correction function is evaluated for selected excited states of the hydrogen molecule within a single-state non-adiabatic treatment. Its qualitative features are studied under the avoided crossing of the $EF$ with the $GK$ state and also for the outer well of the $H\bar{H}$ state. For the $H\bar{H}$ state, a negative mass correction is obtained for the vibrational motion near the outer minimum, which accounts for most of the deviation between experiment and earlier theoretical work.
Enhanced Excited State Population and Coherence via Adiabatic Tunneling Ionization and Excitation
本研究通过绝热隧穿电离和激发方法，显著增强激发态人口和相干性，为强场化学控制和激光应用提供新框架。
We present an implementation of optimal control theory for the first-principles non-adiabatic Ehrenfest Molecular Dynamics model, which describes a condensed matter system by considering classical point-particle nuclei, and quantum electrons, handled in our case with time-dependent density-functional theory. The scheme is demonstrated by optimizing the Coulomb explosion of small Sodium clusters: the algorithm is set to find the optimal femtosecond laser pulses that disintegrate the clusters, for a given total pulse duration, fluence, and cut-off frequency. We describe the numerical details and…
An Automated Framework for Analyzing Structural Evolution in On-the-fly Non-adiabatic Molecular Dynamics Using Autoencoder and Multiple Molecular Descriptors
针对非绝热分子动力学中反应坐标人工分析效率低、依赖专家经验的问题，提出结合自编码器、聚类与信息熵分析的自动化机器学习框架，可高效准确地从轨迹数据中识别反应通道与关键坐标，为激发态动力学机理研究提供新范式。
We extend ring-polymer molecular dynamics (RPMD) to allow for the direct simulation of general, electronically non-adiabatic chemical processes. The kinetically constrained (KC) RPMD method uses the imaginary-time path-integral representation in the set of nuclear coordinates and electronic states to provide continuous equations of motion that describe the quantized, electronically non-adiabatic dynamics of the system. KC-RPMD preserves the favorable properties of the usual RPMD formulation in the position representation, including rigorous detailed balance, time-reversal symmetry, and invaria…
Recently proposed non-adiabatic ring polymer molecular dynamics (NRPMD) approach has shown to provide accurate quantum dynamics by incorporating explicit electronic state descriptions and nuclear quantizations. Here, we present a rigorous derivation of the NRPMD Hamiltonian and investigate its performance on simulating excited state non-adiabatic dynamics. Our derivation is based on the Meyer-Miller-Stock-Thoss (MMST) mapping representation for electronic states and the ring-polymer path-integral description for nuclei, resulting in the same Hamiltonian proposed in the original NRPMD approach.…
We present a perturbation approach rooted in time-dependent density-functional theory to calculate electron hole (eh)-pair excitation spectra during the non-adiabatic vibrational damping of adsorbates on metal surfaces. Our analysis for the benchmark systems CO on Cu(100) and Pt(111) elucidates the surprisingly strong influence of rather short electronic coherence times. We demonstrate how in the limit of short electronic coherence times, as implicitly assumed in prevalent quantum nuclear theories for the vibrational lifetimes as well as electronic friction, band structure effects are washed o…
We introduce the coherent state mapping ring-polymer molecular dynamics (CS-RPMD), a new method that accurately describes electronic non-adiabatic dynamics with explicit nuclear quantization. This new approach is derived by using coherent state mapping representation for the electronic degrees of freedom (DOF) and the ring-polymer path-integral representation for the nuclear DOF. CS-RPMD Hamiltonian does not contain any inter-bead coupling term in the state-dependent potential, which is a key feature that ensures correct electronic Rabi oscillations. Hamilton's equation of motion is used to sa…
A Semiclassical Gaussian Wavepacket Method for Non-Adiabatic Molecular Dynamics
介绍两种用耦合高斯波包的非绝热半经典方法，通过强制假设或变分原理推导经典运动方程，经合理性检验后用于两个非绝热势能场景，变分解冻高斯方法更准确，借助经典轨迹再现非绝热分子动力学。
Quantum molecular dynamics requires an accurate representation of the molecular potential energy surface from a minimal number of electronic structure calculations, particularly for nonadiabatic dynamics where excited states are required. In this paper, we employ pseudospectral sampling of time-dependent Gaussian basis functions for the simulation of non-adiabatic dynamics. Unlike other methods, the pseudospectral Gaussian molecular dynamics tests the Schrödinger equation with $N$ Dirac delta functions located at the centers of the Gaussian functions reducing the scaling of potential energy ev…
We derive the non-adiabatic ring polymer molecular dynamics (RPMD) approach in the phase space of the SU(N) Lie Group. This method, which we refer to as the spin mapping non-adiabatic RPMD (SM-NRPMD), is based on the spin-mapping formalism for the electronic degrees of freedom (DOFs) and ring polymer path-integral description for the nuclear DOFs. Using the Stratonovich-Weyl transform for the electronic DOFs, and the Wigner transform for the nuclear DOFs, we derived an exact expression of the Kubo-transformed time-correlation function (TCF). We further derive the spin mapping non-adiabatic Mat…
We study the many-body dynamics of stimulated Raman adiabatic passage in the presence of on-site interactions. In the classical mean-field limit, explored in Phys. Rev. Lett. {\bf 121}, 250405 (2018), interaction-induced chaos leads to the breakdown of adiabaticity under the quasi-static variation of the parameters, thus producing {\em low} sweep rate boundaries on efficient population transfer. We show that for the corresponding many-body system, alternative quantum pathways from the initial to the target state, open up at even slower sweep rates. These quantum detours avoid the chaotic class…
We present an approach for carrying out non-adiabatic molecular dynamics simulations of systems in which non-adiabatic transitions arise from the coupling between the classical atomic motions and a quasi-continuum of electronic quantum states. Such conditions occur in many research areas, including chemistry at metal surfaces, radiation damage of materials, and warm dense matter physics. The classical atomic motions are governed by stochastic Langevin-like equations, while the quantum electron dynamics is described by a master equation for the populations of the electronic states. These workin…
Classical and quantum light-induced non-adiabaticity in molecular systems
本文综述经典光与量子光诱导的锥形交叉，比较二者特性及其与自然锥形交叉的关系，并通过分子动力学、光谱实例和计算方法展示其可控非绝热效应潜力。
A mixed quantum-classical approach is introduced which allows the dynamical response of molecules driven far from equilibrium to be modeled. This method is applied to the interaction of molecules with intense, short-duration laser pulses. The electronic response of the molecule is described using time-dependent density functional theory (TDDFT) and the resulting Kohn-Sham equations are solved numerically using finite difference techniques in conjunction with local and global adaptations of an underlying grid in curvilinear coordinates. Using this approach, simulations can be carried out for a …
We quantify the non-adiabatic contributions to the vibronic sidebands of equilibrium and explicitly time-resolved non-equilibrium photoelectron spectra for a vibronic model system of Trans-Polyacetylene. Using exact diagonalization, we directly evaluate the sum-over-states expressions for the linear-response photocurrent. We show that spurious peaks appear in the Born-Oppenheimer approximation for the vibronic spectral function, which are not present in the exact spectral function of the system. The effect can be traced back to the factorized nature of the Born-Oppenheimer initial and final ph…
The role of quantum coherence loss in mixed quantum-classical dynamical systems is explored in the context of the theory of quantum decoherence introduced recently by Bittner and Rossky. (J. Chem. Phys. {\bf 103}, 8130 (1995)). This theory, which is based upon the consistent histories interpretation of quantum mechanics, introduces decoherence in the quantum subsystem by carefully considering the relevant time and length scales over which one must consider the effects of phase interference between alternative histories of the classical subsystem. Such alternative histories are an integral part…
Ultralong-range Rydberg molecules provide an exciting testbed for molecular physics at exaggerated scales. In the so-called trilobite and butterfly Rydberg molecules, the Born-Oppenheimer approximation can fail due to strong non-adiabatic couplings arising from the combination of radial oscillations and rapid energy variations in the adiabatic potential energy curves. We utilize an accurate coupled-channel treatment of the vibronic system to observe the breakdown of Born-Oppenheimer physics, such as non-adiabatic trapping and decay of molecular states found near pronounced avoided crossings in…
We present a new non-adiabatic ring polymer molecular dynamics (NRPMD) method based on the spin mapping formalism, which we refer to as the spin-mapping NRPMD (SM-NRPMD) approach. We derive the path-integral partition function expression using the spin coherent state basis for the electronic states and the ring polymer formalism for the nuclear degrees of freedom (DOFs). This partition function provides an efficient sampling of the quantum statistics. Using the basic property of the Stratonovich-Weyl transformation, we derive a Hamiltonian which we propose for the dynamical propagation of the …
The accurate description of large molecular systems in complex environments remains an ongoing challenge for the field of computational chemistry. This problem is even more pronounced for photo-induced processes, as multiple excited electronic states and their corresponding non-adiabatic couplings must be taken into account. Multiscale approaches such as hybrid quantum mechanics/molecular mechanics (QM/MM) offer a balanced compromise between accuracy and computational burden. Here, we introduce an open-source software package (INAQS) for non-adiabatic QM/MM simulations that bridges the samplin…
Molecular Control of Floquet Topological Phase in Non-adiabatic Thouless Pumping
本研究在拓扑Floquet工程框架下研究非绝热Thouless电子泵浦，结合实时含时密度泛函理论与最大局域化Wannier函数，揭示化学基团修饰对Floquet拓扑相的调控机制，为分子拓扑系统设计提供新思路。
We present the APLIP process (Adiabatic Passage by Light Induced Potentials) for the adiabatic transfer of a wave packet from one molecular potential to the displaced ground vibrational state of another. The process uses an intermediate state, which is only slightly populated, and a counterintuitive sequence of light pulses to couple the three molecular states. APLIP shares many features with STIRAP (stimulated Raman adiabatic passage), such as high efficiency and insensitivity to pulse parameters. However, in APLIP there is no two-photon resonance, and the main mechanism for the transport of …
When the interaction between a molecular system and confined light modes in an optical or plasmonic cavity is strong enough to overcome the dissipative process, hybrid light-matter states (polaritons) become the fundamental excitations in the system. The mixing between the light and matter characters modifies the photophysical and photochemical properties. Especially, it was reported that these polaritons can be employed to control photochemical reactions, charge and energy transfer, and other processes. In addition, according to recent studies, vibrational strong coupling can be employed to r…
Using an optical centrifuge to control molecular rotation in an extremely broad range of angular momenta, we study coherent rotational dynamics of nitrogen molecules in the presence of collisions. We cover the range of rotational quantum numbers between J=8 and J=66 at room temperature and study a cross-over between the adiabatic and non-adiabatic regimes of rotational relaxation, which cannot be easily accessed by thermal means. We demonstrate that the rate of rotational decoherence changes by more than an order of magnitude in this range of J values, and show that its dependence on J can be …
Efficient Quantum Simulation of Non-Adiabatic Molecular Dynamics with Precise Electronic Structure
本研究提出一种量子适应的非绝热分子动力学方法，通过曲率驱动跃迁修正和亚微赫特准确的PES计算协议，实现高效且精确的分子动力学模拟。
In this study, two different simple and intuitive semiempirical schemes for computing approximate non-adiabatic coupling vectors (NACVs) between the ground and excited electronic states are presented. The first approximation makes use of Mulliken transition charges, while the second is based on derivative coupling vectors between localized molecular orbitals. Both approximations lend themselves easily to implementation within a whole spectrum of semiempirical quantum-chemical semiempirical methods. Here we present the implementation within the tight-binding DFT and benchmark its performance ag…
We theoretically examine Raman photoassociation of a Bose-Einstein condensate, revisiting stimulated Raman adiabatic passage (STIRAP). Due to collisional mean-field shifts, efficient molecular conversion requires strong coupling and low density, either of which can bring about rogue photodissociation to noncondensate modes. We demonstrate explicitly that rogue transitions are negligible for low excited-state fractions and photodissociation that is slower than the STIRAP timescale. Moreover, we derive a reduced-parameter model of collisions, and thereby find that a gain in the molecular convers…
Mixed quantum-classical mechanics descriptions are critical to modeling coupled electron-nuclear dynamics, i.e. non-adiabatic molecular dynamics, relevant to photochemical and photophysical processes. We argue that, for polyatomic molecules, such mixed dynamics can not be efficiently described in terms of a matrix gauge potential and develop the concept of a `length gauge' effective Hamiltonian, which helps clarifying certain aspects for the popular non-adiabatic computational approaches. In particular, within such an effective Hamiltonain formalism one readily derives the momentum rescaling b…
Dynamics of the molecular geometric phase
本文利用精确分解和量子流体动力学研究分子几何相的动力学演化，证明闭合路径相位满足麦克斯韦-法拉第感应定律，并指出在近似绝热条件下几何相变化可忽略，从而为绝热理想化的适用性提供依据。
The mass-correction functions in the second-order non-adiabatic Hamiltonian are computed for the $^4$He$^+_2$ molecular ion using the variational method, floating explicitly correlated Gaussian functions, and a general coordinate-transformation formalism. When non-adiabatic rovibrational energy levels are computed using these (coordinate-dependent) mass-correction functions and a highly accurate potential energy and diagonal Born-Oppenheimer correction curve, significantly improved theoretical results are obtained for the nine rotational and two rovibrational intervals known from high-resoluti…
Quantum computation promises to provide substantial speedups in many practical applications with a particularly exciting one being the simulation of quantum many-body systems. Adiabatic state preparation (ASP) is one way that quantum computers could recreate and simulate the ground state of a physical system. In this paper we explore a novel approach for classically simulating the time dynamics of ASP with high accuracy, and with only modest computational resources via an adaptive sampling configuration interaction (ASCI) scheme for truncating the Hilbert space to only the most important deter…
Recently, several laser schemes have been proposed to separate racemic mixtures of enantiomers by splitting a molecular beam into subbeams consisting of molecules of definite chirality [Y. Li, C. Bruder, and C. P. Sun, Phys. Rev. Lett. 99, 130403 (2007); X. Li and M. Shapiro, J. Chem. Phys. 132, 194315 (2010)]. These ideas rely on laser-induced effective gauge potentials in an adiabatic basis which lead to a chirality dependent force on the center-of-mass. However, the effect of molecular rotation has been neglected in these studies. Accounting for the full molecular quantum state we find that…
We study theoretically the quantum dynamics and spectroscopy of rovibrational polaritons formed in a model system composed of a single rovibrating diatomic molecule, which interacts with two degenerate, orthogonally polarized modes of an optical Fabry-Pérot cavity. We employ an effective rovibrational Pauli-Fierz Hamiltonian in length gauge representation and identify three-state vibro-polaritonic conical intersections (VPCIs) between singly-excited vibro-polaritonic states in a two-dimensional angular coordinate branching space. The lower and upper vibrational polaritons are of mixed light-ma…
We address the calculation of microcanonical reaction rates for processes involving significant nuclear quantum effects using ring-polymer molecular dynamics (RPMD), both with and without electronically non-adiabatic transitions. After illustrating the shortcomings of the naive free-particle direct-shooting method, in which the temperature of the internal ring-polymer modes is set to the translational energy scale, we investigate alternative strategies based on the expression for the microcanonical rate in terms of the inverse Laplace transform of the thermal reaction rate. It is shown that si…
扫码添加微信好友，提出您的宝贵建议 👇
💡 备注请填写：网站反馈
发表机构由 AI 从论文文本抽取，如发现错误，欢迎反馈修正建议。