Article
Chemistry, Physical
Elisabeth Keller, Theodoros Tsatsoulis, Karsten Reuter, Johannes T. Margraf
Summary: This paper explores how regularization can ameliorate the issues of second-order Moller-Plesset perturbation theory (MP2) for metallic, polarizable, and strongly correlated periodic systems. Two regularized second-order methods are applied to various systems, leading to consistent improvements over the MP2 baseline with different regularizers found to be suitable for different systems.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Operations Research & Management Science
Yingchao Gao, Sandor Zoltan Nemeth, Roman Sznajder
Summary: This paper investigates the properties of the monotone extended second-order cone (MESOC), including computation of its Lyapunov rank, proving its reducibility, and examining the isotonic projection of a cylinder in an ambient space with respect to MESOC. Additionally, a nonlinear complementarity problem on a cylinder is studied, which is equivalent to a suitable mixed complementarity problem, along with a computational example illustrating the applicability of MESOC.
JOURNAL OF OPTIMIZATION THEORY AND APPLICATIONS
(2022)
Article
Chemistry, Physical
Jan-Niklas Boyn, David A. Mazziotti
Summary: Accurately resolving the chemical properties of strongly correlated systems requires the use of electronic structure theories that account for both multi-reference and dynamic correlation effects. This study explores the use of density functional theory as a cost-effective alternative to generate reference orbitals for post-configuration-interaction dynamic correlation calculations.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Chemistry, Physical
Zhenling Wang, Abdulrahman Aldossary, Martin Head-Gordon
Summary: In this paper, the sparsity of the electron repulsion integral (ERI) tensor in second-order Moller-Plesset theory (MP2) is explored. Different approaches to achieving sparsity are compared, and it is found that the orthogonal valence virtual-hard virtual set of virtual orbitals gives the sparsest ERI tensor. The low-rank pair natural orbital (PNO) representation achieves significant rank reduction but requires more memory, while the occupied-specific virtual (OSV) approach has similar memory usage but greater algorithmic complexity.
JOURNAL OF CHEMICAL PHYSICS
(2023)
Article
Chemistry, Physical
Ilia M. Mazin, Alexander Yu Sokolov
Summary: This study presents a new implementation and benchmark of approximations in multireference algebraic diagrammatic construction theory for simulations of neutral electronic excitations and UV/vis spectra of strongly correlated molecular systems. The results demonstrate that the proposed MR-ADC methods outperform third-order single-reference ADC approximation for weakly correlated electronic states and are competitive with equation-of-motion coupled cluster theory results. For states with multireference character, the performance of the MR-ADC methods is similar to that of N-electron valence perturbation theory.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2021)
Article
Automation & Control Systems
Xin He, Rong Hu, Ya-Ping Fang
Summary: In this article, we propose a new second-order dynamical system for linear equality constrained convex optimization problems. We prove the convergence property of this system when certain conditions on the time scaling are satisfied, and show that the convergence rate can be exponential.
IEEE TRANSACTIONS ON AUTOMATIC CONTROL
(2022)
Article
Chemistry, Physical
David Mester, Mihaly Kallay
Summary: This study extends the reduced-cost scheme based on the frozen virtual natural orbital and natural auxiliary function approaches to core excitations. The efficiency of the approximation is evaluated for the second-order algebraic-diagrammatic construction (ADC(2)) method using the core-valence separation (CVS) and density fitting approaches. The results demonstrate significant computational savings with a moderate error, making the approach feasible for larger systems.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2023)
Article
Mathematics
Yi-Teng Hu, Murat Sat
Summary: This paper examines second-order differential pencils with a fixed frozen argument on a finite interval and obtains trace formulae under four different boundary conditions. Despite the different boundary conditions and the corresponding asymptotic behavior of the eigenvalues, the trace formulae share the same form, revealing the impact of the frozen argument.
Article
Engineering, Electrical & Electronic
Muhammad Khalid, Muhammad Usman Khan, Riaz Hussain, Shabana Irshad, Bakhat Ali, Ataualpa Albert Carmo Braga, Muhammad Imran, Amjad Hussain
Summary: Organic compounds with structural alterations at donor and acceptor parts showed promising nonlinear optical responses, with smaller energy band gaps and larger softness magnitudes compared to reference molecule HCPBR. The derivatives exhibited red shift and higher NLO responses, indicating their potential for optoelectronic applications.
OPTICAL AND QUANTUM ELECTRONICS
(2021)
Article
Spectroscopy
Bhagwat Kharat, Mahadevappa Naganathappa, Vasant Jagrut, Ajay Chaudhari
Summary: This study investigates the spectroscopic characterization and second hyperpolarizability of odd spin states of acetonitrile in gas phase and water solvent. The results show that the second hyperpolarizability values for odd spin states are more positive than the first hyperpolarizability, and spin has an effect on spectroscopic parameters except for energy.
SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
(2022)
Article
Mathematics, Applied
S. Priyadarshana, J. Mohapatra, S. R. Pattanaik
Summary: The objective of this work is to provide an efficient and higher-order numerical scheme for the solution of a singularly perturbed 2D time-delayed parabolic convection-diffusion problem. The proposed method combines a central difference scheme and a mid-point upwind scheme on a Shishkin mesh, achieving second-order spatial accuracy in the discrete supremum norm. The effectiveness of the scheme is validated through numerical tests.
APPLIED NUMERICAL MATHEMATICS
(2023)
Article
Mathematics
Sergey Kochetkov, Svetlana A. Krasnova, Victor A. Utkin
Summary: A new class of regulators based on second-order sliding mode control is proposed in this paper. The synthesized control law provides a transient oscillatory process with decaying amplitudes, which converge to zero in finite time. The designed feedback provides an invariance property with respect to smooth external perturbation with less relay amplitude.
Article
Mathematics, Applied
Xuhong Yu, Qingrui Mao
Summary: Diagonalized Legendre spectral methods for solving second-order eigenvalue problems are proposed, which utilize matrix decomposition technique to construct a new class of basis functions that are simultaneously orthogonal in both L2- and H1-inner products. These methods lead to diagonal systems for second-order eigenvalue problems with constant coefficients. Numerical experiments demonstrate their high-order accuracy and significantly improved efficiency, as they simplify the calculation process, reduce the amount of calculation, and effectively avoid the curse of dimensionality of high-dimensional eigenvalue problems.
COMPUTERS & MATHEMATICS WITH APPLICATIONS
(2023)
Article
Mathematics, Applied
Le Van Vinh, Van Nam Tran, Phan Tu Vuong
Summary: This paper considers a second-order dynamical system for solving equilibrium problems in Hilbert spaces and proves the existence and uniqueness of strong global solutions under suitable conditions. The exponential convergence of trajectories is established under strong pseudo-monotonicity and Lipschitz-type conditions. Furthermore, a discrete version of the second-order dynamical system is investigated, which leads to a fixed point-type algorithm with inertial effect and relaxation. The linear convergence of this algorithm is proven under suitable parameter conditions. Numerical experiments are conducted to confirm the theoretical results.
NUMERICAL ALGORITHMS
(2022)
Article
Mathematics, Applied
Lijuan Cheng, Yong Ren
Summary: This paper discusses a class of perturbed second-order stochastic evolution equations and proposes a perturbed equation for the unperturbed one. It demonstrates that the mild solutions of the perturbed and unperturbed equations are close on finite time intervals and as small perturbations tend to zero. A class of stochastic partial differential equations with perturbations is suggested as an application to illustrate the theoretical results.
QUALITATIVE THEORY OF DYNAMICAL SYSTEMS
(2021)
Article
Chemistry, Physical
Jeremy R. Rouxel, Daniel Keefer, Flavia Aleotti, Artur Nenov, Marco Garavelli, Shaul Mukamel
Summary: This study demonstrates the potential of ultrafast electron diffraction in monitoring conical intersection dynamics in molecules, with a focus on hybrid scattering from nuclei and electrons. Specific signal contributions that offer a direct window into conical intersection paths are identified, emphasizing the importance of vibronic coherence in the absence of which these contributions vanish.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2022)
Article
Chemistry, Physical
Francesco Montorsi, Francesco Segatta, Artur Nenov, Shaul Mukamel, Marco Garavelli
Summary: In this study, the multiconfigurational restricted active space self-consistent field RASSCF/RASPT2 method is coupled with the displaced harmonic oscillator (DHO) model to simulate soft X-ray spectroscopy. The method is applied to various second-row elements and small organic molecules, showing sub-eV accuracy in simulating X-ray absorption near-edge structure (XANES) and X-ray photoelectron spectroscopy (XPS). The method is sensitive to spectral shifts in fluorinated ethylene systems, distinguishes stable conformers of the glycine molecule, and accurately captures the vibrationally resolved carbon K-edge spectrum of formaldehyde. Comparisons with other theoretical methods highlight the advantages of using a multireference/multiconfigurational approach.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2022)
Article
Chemistry, Physical
Giacomo Fanciullo, Irene Conti, Pascal Didier, Andrey Klymchenko, Jeremie Leonard, Marco Garavelli, Ivan Rivalta
Summary: A new macroscopic model incorporating contributions from molecular aggregate quenchers was introduced to analyze the decay process of exciton density. The study demonstrated that the model is applicable to molecular systems with ultrafast decays, and the presence of molecular aggregate quenchers can be monitored by evaluating the long time decay of exciton density. This model could potentially be used in future studies for global fitting of experimental data with support from first-principles simulations.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2022)
Article
Chemistry, Physical
Yeonsig Nam, Francesco Montorsi, Daniel Keefer, Stefano M. Cavaletto, Jin Yong Lee, Artur Nenov, Marco Garavelli, Shaul Mukamel
Summary: In this study, we theoretically monitor the photoinduced pi pi*-> n pi* internal conversion process in 4-thiouracil (4TU) using a resonant X-ray probe tuned to the sulfur, oxygen, or nitrogen K-edge. We discuss the capabilities and limitations of the resonant technique and observe specific spectral features for sulfur and nitrogen, as well as an inaccessible transition for oxygen. Overall, this study provides a detailed understanding of the electronic excited-state dynamics and offers insights into the photophysics of thiobases.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2022)
Article
Electrochemistry
Mattia Belotti, Mohsen M. T. El-Tahawy, Nadim Darwish, Marco Garavelli, Simone Ciampi
Summary: This study explores the current response, light intensity, and spectral signatures of the cathodic electrochemiluminescence (ECL) in room temperature ionic liquids (RTILs). It demonstrates the viability of using electrode reactions to generate light emitters in RTILs and discovers that the ECL signal can persist for a certain duration after the removal of the external cathodic pulse due to the stabilization of superoxide.
Article
Chemistry, Analytical
Mattia Belotti, Mohsen M. T. El-Tahawy, Marco Garavelli, Michelle L. Coote, K. Swaminathan Iyer, Simone Ciampi
Summary: The study develops a direct, spatiotemporally resolved optical tracking method to detect and resolve convective disturbances in electrochemical reactivity. It is found that parasitic gas evolving reactions lead to overestimates of macroscopic diffusion coefficients by 10 times. A hypothesis is proposed linking large barriers to inner-sphere redox reactions to the formation of cation-rich overscreening and crowding double layer structures in imidazolium-based ionic liquids.
ANALYTICAL CHEMISTRY
(2023)
Article
Chemistry, Physical
Andy Kaiser, Razan E. Daoud, Francesco Aquilante, Oliver Kuhn, Luca De Vico, Sergey I. Bokarev
Summary: We implemented the Frenkel exciton model into the OpenMolcas program package to calculate collective electronic excited states of molecular aggregates. Our protocol does not rely on diabatization schemes or supermolecule calculations, and the use of Cholesky decomposition for pair interactions improves computational efficiency. We applied our method to two test systems and compared it with the dipole approximation.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2023)
Article
Chemistry, Physical
Giovanni Li Manni, Ignacio Fdez. Galvan, Ali Alavi, Flavia Aleotti, Francesco Aquilante, Jochen Autschbach, Davide Avagliano, Alberto Baiardi, Jie J. Bao, Stefano Battaglia, Letitia Birnoschi, Alejandro Blanco-Gonzalez, Sergey I. Bokarev, Ria Broer, Roberto Cacciari, Paul B. Calio, Rebecca K. Carlson, Rafael Carvalho Couto, Luis Cerdan, Liviu F. Chibotaru, Nicholas F. Chilton, Jonathan Richard Church, Irene Conti, Sonia Coriani, Juliana Cuellar-Zuquin, Razan E. Daoud, Nike Dattani, Piero Decleva, Coen de Graaf, Mickael G. Delcey, Luca De Vico, Werner Dobrautz, Sijia S. Dong, Rulin Feng, Nicolas Ferre, Michael Filatov (Gulak), Laura Gagliardi, Marco Garavelli, Leticia Gonzalez, Yafu Guan, Meiyuan Guo, Matthew R. Hennefarth, Matthew R. Hermes, Chad E. Hoyer, Miquel Huix-Rotllant, Vishal Kumar Jaiswal, Andy Kaiser, Danil S. Kaliakin, Marjan Khamesian, Daniel S. King, Vladislav Kochetov, Marek Krosnicki, Arpit Arun Kumaar, Ernst D. Larsson, Susi Lehtola, Marie-Bernadette Lepetit, Hans Lischka, Pablo Lopez Rios, Marcus Lundberg, Dongxia Ma, Sebastian Mai, Philipp Marquetand, Isabella C. D. Merritt, Francesco Montorsi, Maximilian Morchen, Artur Nenov, Vu Ha Anh Nguyen, Yoshio Nishimoto, Meagan S. Oakley, Massimo Olivucci, Markus Oppel, Daniele Padula, Riddhish Pandharkar, Quan Manh Phung, Felix Plasser, Gerardo Raggi, Elisa Rebolini, Markus Reiher, Ivan Rivalta, Daniel Roca-Sanjuan, Thies Romig, Arta Anushirwan Safari, Aitor Sanchez-Mansilla, Andrew M. Sand, Igor Schapiro, Thais R. Scott, Javier Segarra-Marti, Francesco Segatta, Dumitru-Claudiu Sergentu, Prachi Sharma, Ron Shepard, Yinan Shu, Jakob K. Staab, Tjerk P. Straatsma, Lasse Kragh Sorensen, Bruno Nunes Cabral Tenorio, Donald G. Truhlar, Liviu Ungur, Morgane Vacher, Valera Veryazov, Torben Arne Voss, Oskar Weser, Dihua Wu, Xuchun Yang, David Yarkony, Chen Zhou, J. Patrick Zobel, Roland Lindh
Summary: This article describes the developments of the open-source OpenMolcas chemistry software environment since spring 2020, focusing on the novel functionalities in the stable branch and interfaces with other packages. These developments cover a wide range of topics in computational chemistry and provide an overview of the chemical phenomena and processes that OpenMolcas can address.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2023)
Article
Chemistry, Physical
Francesco Segatta, Daniel Aranda Ruiz, Flavia Aleotti, Martha Yaghoubi, Shaul Mukamel, Marco Garavelli, Fabrizio Santoro, Artur Nenov
Summary: This paper presents an accurate and efficient approach for calculating the linear and nonlinear optical spectroscopy of a closed quantum system. The method includes the effect of ultrafast nonadiabatic dynamics by numerically propagating the nuclear wave packet. The expressions for the evaluation of response functions are recast in a general form and validated using the multiconfiguration time-dependent Hartree method. The application to pyrene reveals the remarkable influence of ultrafast nonadiabatic dynamics on spectral line shapes.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2023)
Article
Chemistry, Multidisciplinary
Abed Mohamadzade, Artur Nenov, Marco Garavelli, Irene Conti, Susanne Ullrich
Summary: Sulfur-substituted nucleobases are efficient in photoinduced intersystem crossing (ISC), making them versatile for various applications. However, a comprehensive understanding of wavelength-dependent changes in IC and ISC events is still lacking.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2023)
Article
Chemistry, Physical
Juliana Cuellar-Zuquin, Ana Julieta Pepino, Ignacio Fdez Galvan, Ivan Rivalta, Francesco Aquilante, Marco Garavelli, Roland Lindh, Javier Segarra-Marti
Summary: We characterized the photochemically relevant conical intersections between different DNA/RNA nucleobases using CASSCF algorithms. Our results show that the size of the active space significantly affects the conical intersection topographies, while the basis set size seems to have a minor effect. We ruled out structural changes as a key factor and highlighted the importance of accurately describing the electronic states involved in these intersections.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2023)
Article
Chemistry, Physical
Henar Mateo-delaFuente, Davide Avagliano, Marco Garavelli, Juan J. Nogueira
Summary: The absorption and emission spectra of luciferine/luciferase were calculated using molecular dynamics simulations, hybrid quantum mechanics/molecular mechanics calculations, and transition density analysis. The presence of the enzyme hampers the torsional motion of the chromophore, reducing the intramolecular charge transfer nature of the absorbing and emitting state. However, a polar environment around the oxygen atom enhances the charge transfer character of the emitting state.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Chemistry, Multidisciplinary
Yeonsig Nam, Huajing Song, Victor M. Freixas, Daniel Keefer, Sebastian Fernandez-Alberti, Jin Yong Lee, Marco Garavelli, Sergei Tretiak, Shaul Mukamel
Summary: Understanding conical intersection (CI) dynamics and subsequent conformational changes is crucial for exploring and controlling photo-reactions in aromatic molecules. In this study, we simulate the photoinduced S-3 to S-1 non-adiabatic dynamics of cyclooctatetraene (COT) and find good agreement with experimental relaxation times. We also investigate the potential of TRUECARS and TRXD to directly probe CI passages in COT, showing that these signals can sensitively monitor key chemical features and resolve ultrafast changes in aromaticity and geometries during the dynamics.
Article
Chemistry, Physical
Giovanni Li Manni, Ignacio Fdez. Galvan, Ali Alavi, Flavia Aleotti, Francesco Aquilante, Jochen Autschbach, Davide Avagliano, Alberto Baiardi, Jie J. Bao, Stefano Battaglia, Letitia Birnoschi, Alejandro Blanco-Gonzalez, Sergey I. Bokarev, Ria Broer, Roberto Cacciari, Paul B. Calio, Rebecca K. Carlson, Rafael Carvalho Couto, Luis Cerdan, Liviu F. Chibotaru, Nicholas F. Chilton, Jonathan Richard Church, Irene Conti, Sonia Coriani, Juliana Cuellar-Zuquin, Razan E. Daoud, Nike Dattani, Piero Decleva, Coen de Graaf, Mickael G. Delcey, Luca De Vico, Werner Dobrautz, Sijia S. Dong, Rulin Feng, Nicolas Ferre, Michael Filatov(Gulak), Laura Gagliardi, Marco Garavelli, Leticia Gonzalez, Yafu Guan, Meiyuan Guo, Matthew R. Hennefarth, Matthew R. Hermes, Chad E. Hoyer, Miquel Huix-Rotllant, Vishal Kumar Jaiswal, Andy Kaiser, Danil S. Kaliakin, Marjan Khamesian, Daniel S. King, Vladislav Kochetov, Marek Krosnicki, Arpit Arun Kumaar, Ernst D. Larsson, Susi Lehtola, Marie-Bernadette Lepetit, Hans Lischka, Pablo Lopez Rios, Marcus Lundberg, Dongxia Ma, Sebastian Mai, Philipp Marquetand, Isabella C. D. Merritt, Francesco Montorsi, Maximilian Morchen, Artur Nenov, Vu Ha Anh Nguyen, Yoshio Nishimoto, Meagan S. Oakley, Massimo Olivucci, Markus Oppel, Daniele Padula, Riddhish Pandharkar, Quan Manh Phung, Felix Plasser, Gerardo Raggi, Elisa Rebolini, Markus Reiher, Ivan Rivalta, Daniel Roca-Sanjuan, Thies Romig, Arta Anushirwan Safari, Aitor Sanchez-Mansilla, Andrew M. Sand, Igor Schapiro, Thais R. Scott, Javier Segarra-Marti, Francesco Segatta, Dumitru-Claudiu Sergentu, Prachi Sharma, Ron Shepard, Yinan Shu, Jakob K. Staab, Tjerk P. Straatsma, Lasse Kragh Sorensen, Bruno Nunes Cabral Tenorio, Donald G. Truhlar, Liviu Ungur, Morgane Vacher, Valera Veryazov, Torben Arne Voss, Oskar Weser, Dihua Wu, Xuchun Yang, David Yarkony, Chen Zhou, J. Patrick Zobel, Roland Lindh
Summary: This article describes the recent developments in the open-source chemistry software environment, OpenMolcas, since spring 2020. It focuses on the new functionalities and interfaces with other packages. The article presents various topics in computational chemistry, including electronic structure theory, electronic spectroscopy simulations, molecular structure optimizations, ab initio molecular dynamics, and other new features. Overall, it highlights the capabilities of OpenMolcas in addressing chemical phenomena and processes, making it an attractive platform for advanced atomistic computer simulations.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2023)