Symmetry Axis Research Articles

The influence of the bounding surface on the structural ordering of short chains of oligoetherimides.

In this study, we have conducted a comparative analysis of the structural ordering of short oligoetherimide chains (dimers) near the bounding surface, depending on the structure of that surface. In order to clarify the possibility of oligoetherimide ordering along the symmetry axes of graphene, two types of bounding surfaces were considered: graphene, with a regular discrete position of interaction centers (carbon atoms), and a smooth, structureless impermeable wall. The chemical structures of the considered dimers consist of two repeating units of BPDA-P3, ODPA-P3, or aBPDA-P3 thermoplastic polyetherimides. Using all-atom molecular dynamics simulations, the process of structural ordering of the dimers near the surface of the graphene or wall was established. The ODPA-P3 and BPDA-P3 dimers form an ordered state near the graphene surface, while the aBPDA-P3 dimers do not demonstrate structural ordering. The simulation results confirmed that the ordering direction of the BPDA-P3 and ODPA-P3 dimers near the graphene surface is chosen randomly. Comparison of the oligoetherimide structure formed near the attracting wall without a symmetrical location of the interaction centers shows the similarity of the ordering of dimers near the graphene surface and the wall. As in the case of the graphene surface, the ordering of oligoetherimide molecules near the structureless wall demonstrates one direction of ordering. Therefore, we confirmed that the key factor for the onset of ordering is the presence of a confining surface, rather than the symmetrical arrangement of interaction centers in the substrate structure.

Ladder top-quark condensation imprints in supercooled electroweak phase transition

The electroweak (EW) phase transition in the early Universe might be supercooled due to the presence of the classical scale invariance involving Beyond the Standard Model (BSM) sectors and the supercooling could persist down till a later epoch around which the QCD chiral phase transition is supposed to take place. Since this supercooling period keeps masslessness for all the six SM quarks, it has simply been argued that the QCD phase transition is the first order, and so is the EW one. However, not only the QCD coupling but also the top Yukawa and the Higgs quartic couplings get strong at around the QCD scale due to the renormalization group running, hence this scenario is potentially subject to a rigorous nonperturbative analysis. In this work, we employ the ladder Schwinger-Dyson (LSD) analysis based on the Cornwall-Jackiw-Tomboulis formalism at the two-loop level in such a gauge-Higgs-Yukawa system. We show that the chiral broken QCD vacuum emerges with the nonperturbative top condensate and the lightness of all six quarks is guaranteed due to the accidental U(1) axial symmetry presented in the top-Higgs sector. We employ a quark-meson model-like description in the mean field approximation to address the impact on the EW phase transition arising due to the top quark condensation at the QCD phase transition epoch. In the model, the LSD results are encoded to constrain the model parameter space. We then observe the cosmological phase transition of the first-order type and discuss the induced gravitational wave (GW) productions. We find that in addition to the conventional GW signals sourced from an expected BSM at around or over the TeV scale, the dynamical topponium-Higgs system can yield another power spectrum sensitive to the BBO, LISA, and DECIGO, etc.

Quantum Field Theory of Black Hole Perturbations with Backreaction: I General Framework

In a seminal work, Hawking showed that natural states for free quantum matter fields on classical spacetimes that solve the spherically symmetric vacuum Einstein equations are KMS states of non-vanishing temperature. Although Hawking’s calculation does not include the backreaction of matter on geometry, it is more than plausible that the corresponding Hawking radiation leads to black hole evaporation which is, in principle, observable. Obviously, an improvement of Hawking’s calculation including backreaction is a problem of quantum gravity. Since no commonly accepted quantum field theory of general relativity is available yet, it has been difficult to reliably derive the backreaction effect. An obvious approach is to use the black hole perturbation theory of a Schwarzschild black hole of fixed mass and to quantize those perturbations. However, it is not clear how to reconcile perturbation theory with gauge invariance beyond linear perturbations. In recent work, we proposed a new approach to this problem that applies when the physical situation has an approximate symmetry, such as homogeneity (cosmology), spherical symmetry (Schwarzschild), or axial symmetry (Kerr). The idea, which is surprisingly feasible, is to first construct the non-perturbative physical (reduced) Hamiltonian of the reduced phase space of fully gauge invariant observables and only then apply perturbation theory directly in terms of observables. The task to construct observables is then disentangled from perturbation theory, thus allowing to unambiguously develop perturbation theory to arbitrary orders. In this first paper of the series we outline and showcase this approach for spherical symmetry and second order in the perturbations for Einstein–Klein–Gordon–Maxwell theory. Details and generalizations to other matter and symmetry and higher orders will appear in subsequent companion papers.

Characterizing Rotational Dynamics and Heterogeneity via Single-Molecule Intensity Measurements.

Dynamic heterogeneity in glassy systems has typically been characterized at the single-molecule level by extracting rotational relaxation time scales from linear dichroism (LD) collected via two orthogonally polarized channels. However, in such measurements, localization precision is diminished due to photons lost relative to collection in a single detection channel. This poses challenges in characterizing rotational and translational dynamics simultaneously, as translational measurements require high localization precision. In this paper, we present a method for extracting rotational dynamics of glassy systems at the single-molecule level from intensity fluctuations of fluorescent probe molecules in a wide-field configuration without the use of a polarizing optical component. Through numerical analysis, we show that LD and intensity measurements probing rotational dynamics report similar, approximately second-order rotational correlation decays even at low signal to noise. Thus, within the assumptions of small, isotropic rotations, LD and intensity autocorrelation analysis should provide identical information on the time scale and heterogeneity of rotational dynamics. We then present experimental results that validate this numerical result, with direct comparison of LD and intensity-based approaches across probe molecules in both polymeric and small-molecule glass formers as well as across optical configurations. Our results demonstrate moderate correlation on a per-probe basis between rotational time scales obtained from both approaches, with deviations consistent with those expected in a dynamically heterogeneous system. We envision that this easily accessible strategy will be of use across disciplines for characterizing single-molecule rotational dynamics in limited signal situations and/or when high-precision localization is required.

EPR study of a copper impurity center in a single crystal of 6-chlorouracil

Single crystals of 6-chlorouracil containing traces of copper were gamma-irradiated at room temperature and studied using EPR spectroscopy. The ionizing radiation induced the conversion of copper impurities, initially present in the host lattice as Copper(I) complexes, into paramagnetic copper(II) complexes. These complexes exhibited intricate EPR spectra characteristic of Copper(II) complex with two ligated nitrogen atoms. Using EPR spectroscopy, the binding site of Cu(II) ions in a single crystal of 6-chlorouracil was determined. It was proposed that planar coordination bonding to the cupric Cu(II) ion, having two pairs of oxygen and nitrogen atoms as ligands, served to bridge neighboring 6-chlorouracil molecules, thereby replacing a pair of hydrogen bonds with stronger Cu-coordination bonding. The spectroscopic parameters, including g tensor, A(63Cu), and A(14N) tensors, closely resemble those previously reported for copper(II) planar centers in similar systems. However, a small deviation in the principal axes of the g and A(63Cu) tensors from axial symmetry suggests a subtle distortion from the ideal planar geometry of the complex. The theoretically derived spectroscopic parameters further corroborate the proposed structure of the complex.

An implicit particle code with exact energy and charge conservation for studies of dense plasmas in axisymmetric geometries

A collisional particle code based on implicit energy- and charge-conserving methods in axisymmetric geometries is presented. A new particle pusher for axisymmetric systems is introduced that is compatible with exact energy and charge conservation and yields improved accuracy compared to other methods. How to appropriately treat all aspects of the algorithm near the r=0 axis of symmetry is described in detail. The axisymmetric model is verified by simulating the free expansion of a plasma sphere in 2D cylindrical and 1D spherical geometries. The algorithm's ability to study the dynamic compression of a dense plasma is illustrated by simulating the dynamic Z-pinch in 1D cylindrical geometry.

From Fractional Quantum Anomalous Hall Smectics to Polar Smectic Metals: Nontrivial Interplay Between Electronic Liquid Crystal Order and Topological Order in Correlated Topological Flat Bands.

Symmetry-breaking orders can not only compete with each other, but also be interwined, and the interwined topological and symmetry-breaking orders make the situation more intriguing. This work examines the archetypal correlated flat band model on a checkerboard lattice at filling ν = 2/3 and we find the unique interplay between smectic charge order and topological order gives rise to two novel quantum states. As the interaction strength increases, the system first transitions from a Fermi liquid into FQAH smectic (FQAHS) state, where FQAH topological order coexists cooperatively with smectic charge order with enlarged ground-state degeneracy and interestingly, the Hall conductivity is σxy = ν = 2/3, different from the band-folding or doping scenarios. Further increasing the interaction strength, the system undergoes another quantum phase transition and evolves into a polar smectic metal (PSM) state. This emergent PSM is an anisotropic non-Fermi liquid, whose interstripe tunneling is irrelevant while it is metallic inside each stripe. Different from the FQAHS and conventional smectic orders, this PSM spontaneously breaks the two-fold rotational symmetry, resulting in a nonzero electric dipole moment and ferroelectric order. In addition to the exotic ground states, large-scale numerical simulations are also used to study low-energy excitations and thermodynamic characteristics. We find the onset temperature of the incompressible FQAHS state, which also coincides with the onset of non-polar smectic order, is dictated by the magneto-roton modes. Above this onset temperature, the PSM state exists at intermediate-temperature regime. Although the T = 0 quantum phase transition between PSM and FQAHS is first order, the thermal FQAHS-PSM transition could be continuous. We expect the features of the exotic states and thermal phase transitions could be accessed in future experiments.

Harnessing complexity: Nonlinear optical phenomena in L-shapes, nanocrescents, and split-ring resonators.

We conduct systematic studies of the optical characteristics of plasmonic nanoparticles that exhibit C2v symmetry. In particular, we analyze three distinct geometric configurations: an L-type shape, a crescent, and a split-ring resonator shaped like the Greek letter π. Optical properties are examined using the finite-difference time-domain method. It is demonstrated that all three shapes exhibit two prominent plasmon modes associated with the two axes of symmetry. This is in addition to a wide range of resonances observed at high frequencies corresponding to quadrupole modes and peaks due to sharp corners. Next, to facilitate nonlinear analysis, we employ a semiclassical hydrodynamic model, where the electron pressure term is explicitly accounted for. This model goes beyond the standard Drude description and enables capturing nonlocal and nonlinear effects. Employing this model enables us to rigorously examine the second-order angular resolved nonlinear optical response of these nanoparticles in each of the three configurations. Two pumping regimes are considered, namely, continuous wave (CW) and pulsed excitations. For CW pumping, we explore the properties of the second harmonic generation (SHG). Polarization and angle-resolved SHG spectra are obtained, revealing strong dependence on the nanoparticle geometry and incident wave polarization. The C2v symmetry is shown to play a key role in determining the polarization states and selection rules of the SHG signal. For pulsed excitations, we discuss the phenomenon of broadband terahertz (THz) generation induced by the difference-frequency generation . It is shown that the THz emission spectra exhibit unique features attributed to the plasmonic resonances and symmetry of the nanoparticles. The polarization of the generated THz waves is also examined, revealing interesting patterns tied to the nanoparticle geometry. To gain deeper insight, we propose an analytical theory that agrees very well with the numerical experiments. The theory shows that the physical origin of the THz radiation is the mixing of various frequency components of the fundamental pulse by the second-order nonlinear susceptibility. An expression for the far-field THz intensity is derived in terms of the incident pulse parameters and the nonlinear response tensor of the nanoparticle. The results presented in this work offer new insights into the linear and nonlinear optical properties of nanoparticles with C2v symmetry. The demonstrated strong SHG response and efficient broadband THz generation hold great promise for applications in nonlinear spectroscopy, nanophotonics, and optoelectronics. The proposed theoretical framework also provides a valuable tool for understanding and predicting the nonlinear behavior of other related nanostructures.

Glycerol-blended chitosan membranes with directional micro-grooves and reduced stiffness improve Schwann cell wound healing

Regenerative medicine is continuously looking for new natural, biocompatible and possibly biodegradable materials, but also mechanically compliant. Chitosan is emerging as a promising FDA-approved biopolymer for tissue engineering, however, its exploitation in regenerative devices is limited by its brittleness and can be further improved, for example by blending it with other materials or by tuning its superficial microstructure. Here, we developed membranes made of chitosan (Chi) and glycerol, by solvent casting, and micro-patterned them with directional geometries having different levels of axial symmetry. These membranes were characterized by light microscopies, atomic force microscopy (AFM), by thermal, mechanical and degradation assays, and also testedin vitroas scaffolds with Schwann cells (SCs). The glycerol-blended Chi membranes are optimized in terms of mechanical properties, and present a physiological-grade Young's modulus (≈0.7 MPa). The directional topographies are effective in directing cell polarization and migration and in particular are highly performant substrates for collective cell migration. Here, we demonstrate that a combination of a soft compliant biomaterial and a topographical micropatterning can improve the integration of these scaffolds with SCs, a fundamental step in the peripheral nerve regeneration process.

Magnetic quadrupolar resonance in a symmetric three-layered plasmonic metasurface

Dark plasmon mode with even symmetry presents an effective way for manipulating light-matter interactions due to its attractive properties of small radiative loss and strongly intensified near-field, which opens up space for both fundamental explorations and optoelectronic device developments. In this paper, we demonstrate magnetic quadrupolar resonance in a symmetric plasmonic metasurface under oblique light incidence. In a three-layered metasurface made of a cross-shaped gold array on top of a magnesium fluoride film backed with a copper ground plane, a magnetic quadrupolar resonance is excited at 37.3 THz with a quality factor of 34, which is four times of the regular magnetic dipolar resonance excited in the same structure. By increasing the incident angle, asymmetry perturbation on the magnetic quadrupolar mode becomes more pronounced as evidenced from its decreased quality factor. In addition, due to the structure symmetry of the used metal cross, the metasurface exhibits polarization-selective excitation of two separate magnetic quadrupolar modes at 37.3 THz and 42.3 THz for the electric field along four symmetry axes of the structure. Our demonstrated distinctive magnetic quadrupolar resonance offers an alternative mode design in plasmonic metamaterials with an improved quality factor, which could be beneficial for metamaterial applications in sensing, optical filtering and infrared emission manipulation etc.

Single-crystal growth, crystal structure, and molecular dynamics of organic–inorganic [NH3(CH2)2NH3]CuBr4

As part of obtaining excellent properties that can be used as lead-free hybrid solar cells, the crystal growth, crystal structure, phase transition temperature, and thermal properties for [NH3(CH2)2NH3]CuBr4 were discussed. The crystal structure at 300 K was determined to be monoclinic by single-crystal X-ray diffraction (XRD) analysis. The phase transition temperatures were determined to be 447 and 473 K, and the results were consistent with the powder XRD patterns. Thermogravimetric analysis revealed thermal stability up to ~ 460 K. The continuous changes in the 1H and 13C chemical shifts and 14N static resonance frequency with increasing temperature are related to variations in the local environment and coordination geometry. The significant differences in activation energies obtained from the 1H and 13C spin–lattice relaxation times (t1ρ) at low and high temperatures were discussed. The activation energy results suggested that the energy barrier at low temperatures was related to the reorientation of the NH3 and CH2 groups around the three-fold symmetry axis, and the energy barrier at high temperatures was related to the reorientation of the [NH3(CH2)2NH3] cation. These physical properties will be provide important insights or potential applications of this crystal.Please check and confirm that the corresponding author and their respective corresponding affiliation have been correctly identified and amend if necessary.OK !

Clustering characteristic diffraction vectors in 4-D STEM data sets from overlapping structures in nanocrystalline and amorphous materials

We describe a method for identifying and clustering diffraction vectors in four-dimensional (4-D) scanning transmission electron microscopy data to determine characteristic diffraction patterns from overlapping structures in projection. First, the data is convolved with a 4-D kernel, then diffraction vectors are identified and clustered using both density-based clustering and a metric that emphasizes rotational symmetries. The method works well for both crystalline and amorphous samples and in high- and low-dose experiments. A simulated dataset of overlapping aluminum nanocrystals provides performance metrics as a function of Poisson noise and the number of overlapping structures. Experimental data from an aluminum nanocrystal sample shows similar performance. For an amorphous Pd77.5Cu6Si16.5 thin film, experiments measuring glassy structure show strong evidence of 4- and 6-fold symmetry structures. A significant background arises from the diffraction of overlapping structures. Quantifying this background helps to separate contributions from single, rotationally symmetric structures vs. apparent symmetries arising from overlapping structures in projection.

VIBRATIONS OF A VERTICAL BEAM ROTATING WITH VARIABLE ANGULAR VELOCITY

An Euler-Bernoulli beam in vertical position rotating about its symmetry axis along its length is considered. The angular velocity is assumed to have small fluctuations about a constant mean velocity. The partial differential equation of motion is derived first. The equation is cast into a non-dimensional form. The natural frequencies are calculated for the pinned-pinned case. Principle parametric resonances such that the fluctuation frequency being close to two times one of the natural frequencies are considered. By employment of the Method of Multiple Scales, an approximate perturbation solution is found. The frequency response diagrams are drawn and the bifurcation points for transition from the trivial solution to the non-trivial solution are calculated. The conditions for which such resonances occur are exploited in the numerical results.

Inhomogeneous fan-shaped surface state induced by isolated Weyl points in acoustic crystals and the associated multi-frequency sound-wave filters

The nontrivial surface states excited by isolated Weyl points (IWPs) have been scarcely studied to date, primarily due to their circumvention from the Nielsen-Ninomiya no-go theorem. In a groundbreaking study on this topic [Adv. Sci., 10, 2207508 (2023)], we discovered that IWPs can generate a novel nontrivial surface state, namely the multi-fold fan-shaped surface state, which we named. Here, we report another type of fan-shaped surface state generated by an IWP surrounded by a closed Weyl nodal wall (WNW). Unlike previous findings, the fan-shaped surface state discovered here exhibits inhomogeneous in spatial distribution, with significantly varying sizes of the fan blades. Moreover, this surface state can be generated by a charge-four IWP protected by the rotation symmetries {000}, {0}, {C2x|0} and the time-reversal symmetry in the space group (SG) No. 198. Importantly, our simulation results of the acoustic crystals in this SG revel that the inhomogeneous fan-shaped surface state can provide multiple channels for acoustic wave transmission without energy dissipation, demonstrating that this kind of nontrivial surface state offers an effective mechanism for designing multi-frequency acoustic wave filters and selectors.

Compressibility and shear compliance of a pore possessing an (n + 1)-Fold axis of symmetry via the use of a conformal mapping function containing an arbitrary number of terms

We propose a simple yet effective method to determine the compressibility and the shear compliance of a pore possessing an (n + 1)-fold axis of symmetry with n ≥ 2 embedded in an infinite isotropic elastic body. The conformal mapping function which maps the exterior of the pore onto the exterior of the unit circle in the image plane contains an arbitrary number of terms. When the mapping function has N+1 terms, the compressibility and shear compliance are found by solving, respectively, sets of N and 2 N coupled linear algebraic equations. Detailed numerical results for the compressibility and shear compliance of equilateral polygonal holes and a five-pointed star shaped hole are presented to demonstrate the proposed solution method.

Nematic Ising superconductivity with hidden magnetism in few-layer 6R-TaS2

In van der Waals heterostructures (vdWHs), the manipulation of interlayer stacking/coupling allows for the construction of customizable quantum systems exhibiting exotic physics. An illustrative example is the diverse range of states of matter achieved through varying the proximity coupling between two-dimensional (2D) quantum spin liquid (QSL) and superconductors within the TaS2 family. This study presents a demonstration of the intertwined physics of spontaneous rotational symmetry breaking, hidden magnetism, and Ising superconductivity (SC) in the three-fold rotationally symmetric, non-magnetic natural vdWHs 6R-TaS2. A distinctive phase emerges in 6R-TaS2 below a characteristic temperature (T*) of approximately 30 K, which is characterized by a remarkable set of features, including a giant extrinsic anomalous Hall effect (AHE), Kondo screening, magnetic field-tunable thermal hysteresis, and nematic magneto-resistance. At lower temperatures, a coexistence of nematicity and Kondo screening with Ising superconductivity is observed, providing compelling evidence of hidden magnetism within a superconductor. This research not only sheds light on unexpected emergent physics resulting from the coupling of itinerant electrons and localized/correlated electrons in natural vdWHs but also emphasizes the potential for tailoring exotic quantum states through the manipulation of interlayer interactions.

Investigation of biological activity of oxindole semicarbazones based copper (II) complexes: Synthesis, antimicrobial activities and molecular modelling

Copper (II) acetate reacted with 2-oxindole semicarbazone (2-Hoxsc, H1L), 3-methyl 2-oxindole semicarbazone (3-MeHoxsc, H2L) and 6-Chloro-2-oxindole semicarbazone (6-ClHoxsc, H3L) in 1:2 (M:L) molar ratio to form complexes of general formula, [Cu(L2)] (1L, 1; 2L 2; 3L 3. Stoichiometric ratio of complexes was established using UV–Vis spectroscopy. All the complexes were characterised by the CHN analysis, IR, ESR spectroscopy and Mass spectrometry. From the ESR spectrum, g values obtained (g‖ = 2.20; g⊥ = 2.05) for complex 2 confirms axial symmetry for this complex, whereas a broad isotropic signal in 1 and 3 (giso = 2.060, 1; 2.057, 3) indicates extensive exchange coupling. All the synthesized compounds (ligands and complexes) complexes were examined for their anti-tubercular activity against M. tuberculosis H37RV strain. Compounds were also tested for their anti-bacterial (B. subtilis, K. pneumonia) and antifungal (C. auris, C. albicans) activities. Biological investigations revealed that the antimicrobial activities (anti-TB, antibacterial and antifungal) of ligands get improved on complexation with Cu (II) due to formation of chelate ring, which can make the ligand a more powerful biological agent. Complex 3 has shown excellent anti-TB (MIC = 1.6 g/ml) and antibacterial (ZOI = 26 mm at 5 mg/mL) activities. Strong binding of complex 3 was observed (Kb = 24.22 × 105 M−1) with Human Serum Albumin (HSA) using fluorescence spectroscopy. Molecular modelling of complex 3 was also done with the active site of amino acid of M. tuberculosis enoyl reductase. The minimal binding energy of −10.1 kcal/mol indicated significant intermolecular interaction between M. tuberculosis enoyl reductase and complex 3 and is in well agreement with experimental data.

Quasi-equilibrium growth of inch-scale single-crystal monolayer α-In2Se3 on fluor-phlogopite

Epitaxial growth of two-dimensional (2D) materials with uniform orientation has been previously realized by introducing a small binding energy difference between the two locally most stable orientations. However, this small energy difference can be easily disturbed by uncontrollable dynamics during the growth process, limiting its practical applications. Herein, we propose a quasi-equilibrium growth (QEG) strategy to synthesize inch-scale monolayer α-In2Se3 single crystals, a semiconductor with ferroelectric properties, on fluor-phlogopite substrates. The QEG facilitates the discrimination of small differences in binding energy between the two locally most stable orientations, realizing robust single-orientation epitaxy within a broad growth window. Thus, single-crystal α-In2Se3 film can be epitaxially grown on fluor-phlogopite, the cleavage surface atomic layer of which has the same 3-fold rotational symmetry with α-In2Se3. The resulting crystalline quality enables high electron mobility up to 117.2 cm2 V−1 s−1 in α-In2Se3 ferroelectric field-effect transistors, exhibiting reliable nonvolatile memory performance with long retention time and robust cycling endurance. In brief, the developed QEG method provides a route for preparing larger-area single-crystal 2D materials and a promising opportunity for applications of 2D ferroelectric devices and nanoelectronics.

Cartan monopoles

The effective Hamiltonians for chiral supersymmetric gauge theories at small spatial volume are generalizations of the Hamiltonians describing the motion of a scalar or a spinor particle in a field of Dirac monopoles (we are dealing in fact with a certain lattice of monopoles supplemented with a periodic singular potential). The gauge fields in such Hamiltonians belong to the Cartan subalgebras of the corresponding gauge algebras. Such a construction exists for all groups admitting complex representations, i.e., for SU(N≥3), Spin(4n+2) with n≥1 and E6. We give explicit expressions for these Hamiltonians for SU(3), SU(4)≃Spin(6) and for SU(5). The simplified version of such a Hamiltonian, deprived of fermion terms, of the extra scalar potential and when only one node of the lattice is taken into consideration, describe a 3r-dimensional motion (r being the rank of the group) in the field what we call a “Cartan monopole.” As is the case for the ordinary monopole, the Lagrangian of this system enjoys gauge symmetry, rotational symmetry, and the parameter, generalizing the notion of magnetic charge for Cartan monopoles, is quantized. Published by the American Physical Society 2024

Derivative learning of tensorial quantities-Predicting finite temperature infrared spectra from first principles.

We develop a strategy that integrates machine learning and first-principles calculations to achieve technically accurate predictions of infrared spectra. In particular, the methodology allows one to predict infrared spectra for complex systems at finite temperatures. The method's effectiveness is demonstrated in challenging scenarios, such as the analysis of water and the organic-inorganic halide perovskite MAPbI3, where our results consistently align with experimental data. A distinctive feature of the methodology is the incorporation of derivative learning, which proves indispensable for obtaining accurate polarization data in bulk materials and facilitates the training of a machine learning surrogate model of the polarization adapted to rotational and translational symmetries. We achieve polarization prediction accuracies of about 1% for the water dimer by training only on the predicted Born effective charges.