Dr. Alexander Croy

Dr. Croys Forschungsschwerpunkt liegt auf rechnergestützten Verfahren, insbesondere auf Techniken des maschinellen Lernens und Simulationen zur Entwicklung und Beschreibung von Nanomaterialien. Zu seinen Forschungsinteressen zählen auch die elektronische Geruchswahrnehmung und die damit verbundenen interdisziplinären Herausforderungen. Er ist als Akademischer Rat am Lehrstuhl für Physikalische und Theoretische Chemie tätig.

Alexander Croy, Dr.
Wiss. Mitarbeiter | akad. Rat
Raum 105
Lessingstraße 4
07743 Jena Google Maps – LageplanExterner Link

26 Publikationen filtern

Die Publikationen filtern

Hervorgehobene Autoren sind Angehörige der Universität Jena.

  1. Semiconductor Bloch equations in Wannier gauge with well-behaved dephasing

    ErscheinungsjahrStatusPrüfung ausstehendErschienen in:Computer physics communications : an international journal and program library for computational physics and physical chemistry M. Thümmler, T. Lettau, A. Croy, U. Peschel, S. Gräfe
    The semiconductor Bloch equations (SBEs) with a dephasing operator for the microscopic polarizations are a well established approach to simulate high-harmonic spectra in solids. We discuss the impact of the dephasing operator on the stability of the numerical integration of the SBEs in the Wannier gauge. It is shown that the commonly used phenomenological approach to apply dephasing is ill-defined in the presence of band crossings and leads to artifacts in the carrier distribution. They are caused by rapid changes of the dephasing operator matrix elements in the Wannier gauge, which render the convergence of the simulation in the stationary basis infeasible. In the comoving basis, also called Houston basis, these rapid changes can be resolved, but only at the cost of a largely increased computation time. As a remedy, we propose a modification of the dephasing operator with reduced magnitude in energetically close subspaces. This approach removes the artifacts in the carrier distribution and significantly speeds up the calculations, while affecting the high-harmonic spectrum only marginally. To foster further development, we provide our parallelized source code.
    Universitätsbibliographie Jena:
    fsu_mods_00029532Externer Link

  2. High-Performance Phototransistor Based on a 2D Polybenzimidazole Polymer

    ErscheinungsjahrErschienen in:Advanced Materials A. Prasoon, P. Dacha, H. Zhang, E. Unsal, M. Hambsch, A. Croy, S. Fu, N. Ngan Nguyen, K. Liu, H. Qi, S. Chung, M. Jeong, L. Gao, U. Kaiser, K. Cho, H. Wang, R. Dong, G. Cuniberti, M. Bonn, S. Mannsfeld, X. Feng
    Universitätsbibliographie Jena:
    fsu_mods_00025285Externer Link

  4. MORE-Q, a dataset for molecular olfactorial receptor engineering by quantum mechanics

    ErscheinungsjahrErschienen in:Scientific data L. Chen, L. Medrano Sandonas, P. Traber, A. Dianat, N. Tverdokhleb, M. Hurevich, S. Yitzchaik, R. Gutierrez, A. Croy, G. Cuniberti
    We introduce the MORE-Q dataset, a quantum-mechanical (QM) dataset encompassing the structural and electronic data of non-covalent molecular sensors formed by combining 18 mucin-derived olfactorial receptors with 102 body odor volatilome (BOV) molecules. To have a better understanding of their intra- and inter-molecular interactions, we have performed accurate QM calculations in different stages of the sensor design and, accordingly, MORE-Q splits into three subsets: i) MORE-Q-G1: QM data of 18 receptors and 102 BOV molecules, ii) MORE-Q-G2: QM data of 23,838 BOV-receptor configurations, and iii) MORE-Q-G3: QM data of 1,836 BOV-receptor-graphene systems. Each subset involves geometries optimized using GFN2-xTB with D4 dispersion correction and up to 39 physicochemical properties, including global and local properties as well as binding features, all computed at the tightly converged PBE+D3 level of theory. By addressing BOV-receptor-graphene systems from a QM perspective, MORE-Q can serve as a benchmark dataset for state-of-the-art machine learning methods developed to predict binding features. This, in turn, can provide valuable insights for developing the next-generation mucin-derived olfactory receptor sensing devices.
    Universitätsbibliographie Jena:
    fsu_mods_00022155Externer Link

  5. Monosaccharide-Derived Enantioselectivity in SWCNT Chemoresistive VOC Sensing

    ErscheinungsjahrErschienen in:Chemistry: a European Journal A. Shitrit, Y. Sukhran, N. Tverdokhleb, L. Chen, A. Dianat, R. Gutierrez, S. Körbel, A. Croy, G. Cuniberti, M. Hurevich, S. Yitzchaik
    Semiconducting single-walled carbon nanotubes (sc-SWCNTs) are of great potential for vapor sensing. However, sc-SWCNTs lack recognition features for discriminating between sparsely functionalized moieties, molecules with similar structural features, and enantiomer pairs. This becomes a major setback in discriminating between volatile organic compounds (VOCs). Here, we used two galactosides decorated with aromatic groups as a recognition layer in chemoresistive sc-SWCNT sensors to produce chiral preference toward six terpenoid enantiomers. The multichirality and multifunctionality of a monosaccharide scaffold were exploited to maximize the limited interacting features associated with VOCs. The developed system establishes a robust and tunable platform for enantioselective gas sensing.
    Universitätsbibliographie Jena:
    fsu_mods_00028980Externer Link

  6. A dataset of laymen olfactory perception for 74 mono-molecular odors

    ErscheinungsjahrErschienen in:Scientific data A. Bierling, A. Croy, T. Jesgarzewsky, M. Rommel, G. Cuniberti, T. Hummel, I. Croy
    The molecular structure of an odor determines whether and how it is perceived by humans. However, the principles of how odorant chemistry links to perceptual patterns remain largely unknown and are primarily studied using odor rating datasets from highly trained olfactory experts, such as perfumers. This limits our knowledge of typical odor perception and its variability over individuals. We provide a dataset featuring free descriptions, evaluative ratings, and qualitative labels for 74 chemically diverse mono-molecular odorants, rated by a large sample of young adults. A total of 1,227 participants described and rated the odors, and completed questionnaires covering their demographic background, personality traits, and the role of olfaction in their daily lives. The dataset offers a valuable foundation for research aimed at understanding the fundamentals of olfactory perception.
    Universitätsbibliographie Jena:
    fsu_mods_00022143Externer Link

  7. A standardized lexicon of body odor words crafted from 17 countries

    ErscheinungsjahrErschienen in:Scientific data A. Bierling, A. Croy, F. Bilem, L. Bloy, F. Ho, A. Jimenez, P. Kyjaková, M. Mastinu, N. Power Guerra, U. Sailer, A. Schirmer, E. Silva, V. Surakka, L. Takau, E. Thunell, K. Verma, B. Żyżelewicz, A. Majid, I. Croy
    Body odors offer a unique window into the physiological and psychological profile of the emitter. This information, broadcast in nonverbal communication, significantly shapes social interactions. However, effectively digitizing body odors requires a precise framework for perceptual operationalization. Previous research has used a very limited number of verbal terms, such as pleasant, intense, or attractive, which fails to adequately capture qualitative differences. To address this gap, we elicited body odor descriptions from 2,607 participants across 17 countries and 13 languages. All these descriptions are presented here in one dataset, together with a condensed list of 25 body odor words (BOW). Those terms reliably differentiated between body states, and were validated in a separate study with a different group of 155 perceivers. The dataset, available as a web application, provides a novel operationalization of body odor impressions, which is a precondition for studying olfaction in human nonverbal communication, for perception-based digitization of body odors and for comparative studies.
    Universitätsbibliographie Jena:
    fsu_mods_00022154Externer Link

  8. Investigation Into the Properties of γ-Valerolactone and γ-Butyrolactone Imide-Based Electrolytes for Lithium-Ion Batteries

    ErscheinungsjahrErschienen in:Battery Energy K. Teoh, W. Schulze, Z. Song, A. Croy, J. Gómez Urbano, S. Gräfe, A. Balducci
    This study presents a detailed comparative study of lactone-based electrolytes (γ-valerolactone, GVL and γ-butyrolactone, GBL) combined with lithium imide-based salts, namely lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and lithium bis(fluoromethanesulfonyl)imide (LiFSI). Propylene carbonate is employed as a reference electrolyte solvent. The physicochemical properties of these electrolyte systems are determined experimentally and further calculated using our developed computational model. Besides, in-silico investigations are used to reveal valuable insights into the molecular interactions of the electrolyte components, such as self-diffusion coefficients and radial distribution functions. Furthermore, the suitability of lactone-based electrolytes for electrochemical applications is demonstrated by their promising rate capability and cycling stability over 200 cycles in graphite half-cells, especially with 1 M LiTFSI and 2 wt% vinylene carbonate, together with their favorable performance on lithium iron phosphate. An excellent capacity retention achieved in a full-cell configuration (> 80% after 200 cycles) further validates the potential of lactones as battery solvent alternatives, with GVL standing out due to its bio-based origin.
    Universitätsbibliographie Jena:
    fsu_mods_00028569Externer Link

  9. From Local Atomic Environments to Molecular Information Entropy

    ErscheinungsjahrErschienen in:ACS Omega A. Croy
    The similarity of local atomic environments is an important concept in many machine learning techniques, which find applications in computational chemistry and material science. Here, we present and discuss a connection between the information entropy and the similarity matrix of a molecule. The resulting entropy can be used as a measure of the complexity of a molecule. Exemplarily, we introduce and evaluate two specific choices for defining the similarity: one is based on a SMILES representation of local substructures, and the other is based on the SOAP kernel. By tuning the sensitivity of the latter, we can achieve good agreement between the respective entropies. Finally, we consider the entropy of two molecules in a mixture. The gain of entropy due to the mixing can be used as a similarity measure of the molecules. We compare this measure to the average and best-match kernel. The results indicate a connection between the different approaches and demonstrate the usefulness and broad applicability of the similarity-based entropy approach.
    Universitätsbibliographie Jena:
    fsu_mods_00012828Externer Link

  11. Tailoring phosphine ligands for improved C-H activation: insights from Δ-machine learning

    ErscheinungsjahrErschienen in:Digital Discovery: a journal for new thinking on machine learning, robotics and AI T. Huang, R. Geitner, A. Croy, S. Gräfe
    Transition metal complexes have played crucial roles in various homogeneous catalytic processes due to their exceptional versatility. This adaptability stems not only from the central metal ions but also from the vast array of choices of the ligand spheres, which form an enormously large chemical space. For example, Rh complexes, with a well-designed ligand sphere, are known to be efficient in catalyzing the C-H activation process in alkanes. To investigate the structure-property relation of the Rh complex and identify the optimal ligand that minimizes the calculated reaction energy ΔE of an alkane C-H activation, we have applied a Δ-machine learning method trained on various features to study 1743 pairs of reactants (Rh(PLP)(Cl)(CO)) and intermediates (Rh(PLP)(Cl)(CO)(H)(propyl)). Our findings demonstrate that the models exhibit robust predictive performance when trained on features derived from electron density (R² = 0.816), and SOAPs (R² = 0.819), a set of position-based descriptors. Leveraging the model trained on xTB-SOAPs that only depend on the xTB-equilibrium structures, we propose an efficient and accurate screening procedure to explore the extensive chemical space of bisphosphine ligands. By applying this screening procedure, we identify ten newly selected reactant-intermediate pairs with an average ΔE of 33.2 kJ mol−¹, remarkably lower than the average ΔE of the original data set of 68.0 kJ mol−¹. This underscores the efficacy of our screening procedure in pinpointing structures with significantly lower energy levels.
    Universitätsbibliographie Jena:
    fsu_mods_00013567Externer Link

  12. Site-selective chemical reactions by on-water surface sequential assembly

    ErscheinungsjahrErschienen in:Nature Communications A. Prasoon, X. Yu, M. Hambsch, D. Bodesheim, K. Liu, A. Zacarias, N. Nguyen, T. Seki, A. Dianat, A. Croy, G. Cuniberti, P. Fontaine, Y. Nagata, S. Mannsfeld, R. Dong, M. Bonn, X. Feng
    Controlling site-selectivity and reactivity in chemical reactions continues to be a key challenge in modern synthetic chemistry. Here, we demonstrate the discovery of site-selective chemical reactions on the water surface via a sequential assembly approach. A negatively charged surfactant monolayer on the water surface guides the electrostatically driven, epitaxial, and aligned assembly of reagent amino-substituted porphyrin molecules, resulting in a well-defined J-aggregated structure. This constrained geometry of the porphyrin molecules prompts the subsequent directional alignment of the perylenetetracarboxylic dianhydride reagent, enabling the selective formation of a one-sided imide bond between porphyrin and reagent. Surface-specific in-situ spectroscopies reveal the underlying mechanism of the dynamic interface that promotes multilayer growth of the site-selective imide product. The site-selective reaction on the water surface is further demonstrated by three reversible and irreversible chemical reactions, such as imide-, imine-, and 1, 3-diazole (imidazole)- bonds involving porphyrin molecules. This unique sequential assembly approach enables site-selective chemical reactions that can bring on-water surface synthesis to the forefront of modern organic chemistry.
    Universitätsbibliographie Jena:
    fsu_mods_00009561Externer Link
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