Article
Chemistry, Physical
Dhiksha Sharma, Tapta Kanchan Roy
Summary: This study benchmarks the accuracy and convergence of different electronic basis set families for anharmonic molecular vibrational spectroscopic calculations, revealing significant differences between various families, particularly for large molecules.
JOURNAL OF PHYSICAL CHEMISTRY A
(2023)
Article
Chemistry, Physical
Marcelo T. de Oliveira, Julia M. A. Alves, Natalia L. Vrech, Ataualpa A. C. Braga, Cristina A. Barboza
Summary: The application of various density functional approximations (DFAs) in computational studies of carbocations lacks consensus and a rigorous benchmark investigation. To close this gap, the CARBO33 dataset is utilized to evaluate 107 DFT methods, with a specific focus on double hybrid density functionals. The results indicate that certain lower rung DFAs perform better than higher rung DFAs, and double hybrids DSD-PBEP86-NL and omega B97X-2-D3(BJ) show the best overall performance. The popular B3LYP method exhibits poor performance and is not recommended for carbocations. Rating: 8/10
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Chemistry, Physical
Edoardo Spadetto, Pier Herman Theodoor Philipsen, Arno Foerster, Lucas Visscher
Summary: Pair atomic density fitting (PADF) is a promising strategy to decrease the scaling of quantum chemical methods for calculating correlation energy, but it can introduce large errors. This study introduces an alternative methodology to overcome the problem associated with PADF, using regularization and projection techniques. The accuracy and efficiency of this approach are assessed numerically using different basis sets, and the results demonstrate its effectiveness and computational efficiency.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2023)
Article
Chemistry, Physical
Jan Wilhelm, Patrick Seewald, Dorothea Golze
Summary: GW is an accurate method for computing electron addition and removal energies, but its conventional implementation has high computational cost, limiting its application to many systems. A low-scaling GW algorithm with improved accuracy was presented, demonstrating strong size-dependent variation in the fundamental gap of phosphorene nanosheets when applied.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2021)
Article
Chemistry, Physical
Brent R. Westbrook, E. Michael Valencia, Spencer C. Rushing, Gregory S. Tschumper, Ryan C. Fortenberry
Summary: This study offers a theoretical prediction for the fundamental vibrational frequency of B-N stretch in BH3NH3 with high accuracy, and includes various resonances effects, making it one of the most accurate computational data available.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Article
Chemistry, Physical
Chaoqun Zhang, Lan Cheng
Summary: Benchmark spinor-based relativistic coupled-cluster calculations were performed to determine the ionization energies of the uranium atom, the uranium monoxide molecule (UO), and the uranium dioxide molecule (UO2), as well as the bond dissociation energies of UO and UO2. The accuracy of the calculations in accounting for relativistic, electron -correlation, and basis-set effects was analyzed. The results demonstrate the unique applicability of the spinor representation of quantum-chemical methods to uranium-containing atomic and molecular species with uranium oxidation states ranging from U(0) to U(V).
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2022)
Article
Chemistry, Physical
Chaoqun Zhang, Lan Cheng
Summary: This study reports benchmark spinor-based relativistic coupled-cluster calculations for the ionization energies and bond dissociation energies of uranium-containing atomic and molecular species. The accuracy of these calculations in handling relativistic, electron-correlation, and basis-set effects is analyzed. The results demonstrate the unique applicability of spinor representation in quantum-chemical methods for uranium species with various oxidation states.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2022)
Article
Chemistry, Physical
Ryan C. Fortenberry, Joseph S. Francisco
Summary: The study investigates the molecular structure and spectroscopic properties of HSO2 under simulated Venusian atmospheric conditions, revealing its potential high dipole moment and intense antisymmetric S-O stretching frequency. The research findings provide important reference information for further understanding the kinetic properties of HSO2.
JOURNAL OF CHEMICAL PHYSICS
(2021)
Article
Chemistry, Physical
Timothy J. Callow, Benjamin Pearce, Nikitas Gidopoulos
Summary: This paper investigates the behavior of electrons in zero external magnetic field using the Kohn-Sham scheme of density functional theory (DFT) or spin-density functional theory (SDFT). It is found that correcting the closed-shell approximation for open-shell systems allows the approximate DFT xc functionals to be as accurate as those in SDFT. Additionally, it is discovered that the KS equations of SDFT emerge as the generalized KS equations of DFT in the zero magnetic field limit, establishing a previously unknown link between the two theories.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Chemistry, Physical
John F. Stanton
Summary: The study investigates the marked anharmonicity of the CC stretching mode in the ethynyl radical using a vibronic coupling model, attributing the large difference between the harmonic frequency and the fundamental level to vibronic interaction between electronic states. The profound vibronic influence due to strong tuning of gap energy by the CC stretch mode is highlighted, emphasizing the advantage of equation-of-motion CC methods for calculations.
JOURNAL OF PHYSICAL CHEMISTRY A
(2021)
Article
Chemistry, Physical
Julia Netz, Alexander O. Mitrushchenkov, Andreas Koehn
Summary: The study reveals that mean-field approaches may lead to significant errors in calculating spin-orbital coupling matrix elements, with the one-center approximation being a more accurate choice for the examples in the test set.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2021)
Article
Chemistry, Physical
Yuri Alexandre Aoto
Summary: This article explores the accuracy of coupled-cluster theory by examining the geometry of the coupled-cluster wave function manifold within the space of n-electron wave functions. The findings suggest that the coupled-cluster manifold, which is curved, is closer to the full-configuration interaction (FCI) wave function than the flat configuration interaction manifold. The study also provides insights into the failure of the coupled-cluster approach for multireference systems.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Multidisciplinary Sciences
Qiyuan Zhao, Sai Mahit Vaddadi, Michael Woulfe, Lawal A. Ogunfowora, Sanjay S. Garimella, Olexandr Isayev, Brett M. Savoie
Summary: The concept of a graphically-defined model reaction has been used to address the data gap in existing reaction transition state (TS) databases. The resulting dataset, called the Reaction Graph Depth 1 (RGD1) dataset, is composed of 176,992 organic reactions with validated TS and various other properties. RGD1 is the largest and most chemically diverse TS dataset published to date, and can be used to develop novel machine learning models for predicting reaction properties.
Article
Chemistry, Physical
Michael Glasbrenner, Daniel Graf, Christian Ochsenfeld
Summary: A method for computing NMR shieldings using direct RPA is presented, with accuracy depending on the DFT reference orbitals and amount of Hartree-Fock exchange. Results show that shieldings with Hartree-Fock reference are more accurate than MP2 and comparable to CCSD shieldings. At least triple-zeta basis sets are required for reliable results in basis set convergence analysis.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2022)
Article
Chemistry, Physical
Dirk Bakowies
Summary: ATOMIC is a thermochemistry protocol that evaluates atomization energies and enthalpies of formation using bond separation reactions. ATOMIC-2 is an improved version that increases computational efficiency, accuracy, and adds an error and uncertainty model.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2022)
Article
Chemistry, Physical
Tapta Kanchan Roy, Vladimir Kopysov, Aleksandr Pereverzev, Jiri Sebek, R. Benny Gerber, Oleg Boyarkin
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2018)
Article
Chemistry, Multidisciplinary
Subrata Banik, Ankit Kumar Sansi, Shiv Nandan, Tapta Kanchan Roy
Article
Chemistry, Multidisciplinary
Tania Kalsi, Hrishit Mitra, Tapta Kanchan Roy, Sachin Kumar Godara, Pragati Kumar
CRYSTAL GROWTH & DESIGN
(2020)
Article
Chemistry, Physical
Tapta Kanchan Roy, R. Benny Gerber
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2020)
Article
Chemistry, Physical
Tapta Kanchan Roy
Summary: This study investigates the performance of vibrational structure calculations beyond the harmonic approximation using the vibrational self-consistent field method with second-order perturbation corrections (VSCF-PT2) and accurate potential energy surfaces (PESs) obtained from various coupled-cluster electronic structure theories. The accuracy of anharmonic calculations depends on the electronic structure theory used, with CCSD and CCSD(T) showing promising results. The results suggest that VSCF-PT2 theory computed at the CCSD(T) potential offers a good cost/accuracy ratio.
JOURNAL OF PHYSICAL CHEMISTRY A
(2022)
Article
Chemistry, Physical
Suchismita Subhadarshini, J. Shanthi Sravan, Omprakash Sarkar, S. Venkata Mohan, Tapta Kanchan Roy, Tushar Jana
Summary: In this study, a high-molecular weight sulfonated oxybispolybenzimidazole (MSOPBI) membrane was synthesized and tested in a microbial fuel cell (MFC). Compared to the traditional Nafion membrane, the MSOPBI membrane displayed better properties including moderate ion exchange capacity, good proton conductivity, low dimensional swelling, and enhanced mechanical strength. The MFC operation with the MSOPBI membrane showed higher power density and increased bioelectrochemical activity. Therefore, the newly synthesized MSOPBI membrane proves effective for the production of renewable energy and wastewater treatment in MFCs.
ACS APPLIED ENERGY MATERIALS
(2023)
Article
Chemistry, Physical
Dhiksha Sharma, Tapta Kanchan Roy
Summary: This study benchmarks the accuracy and convergence of different electronic basis set families for anharmonic molecular vibrational spectroscopic calculations, revealing significant differences between various families, particularly for large molecules.
JOURNAL OF PHYSICAL CHEMISTRY A
(2023)
Article
Chemistry, Multidisciplinary
Amir Fayaz, Tapta Kanchan Roy, Subrata Banik
Summary: This study systematically investigates the effect of non-local Hartree-Fock exchange term in density functional methods on the vibrational description of polyatomic molecules. The results show that the errors of different functionals with different amounts of HF exchange term can be well fitted with cubic polynomials. The accuracy of vibrational frequencies is sensitive to the HF exchange, with different types of vibrations showing different degrees of sensitivity.
JOURNAL OF CHEMICAL SCIENCES
(2022)
Article
Chemistry, Multidisciplinary
Kanika Jain, Naresh Duvva, Tapta Kanchan Roy, Lingamallu Giribabu, Raghu Chitta
Summary: In this study, novel porphyrin hosts functionalized with phenothiazine moieties were synthesized for selective interaction and encapsulation with fullerenes C-60 and C-70. Experimental results confirmed the formation of host-guest complexes with fullerenes and revealed photo-induced electron transfer between the phenothiazine-porphyrin system and fullerenes.
NEW JOURNAL OF CHEMISTRY
(2021)
Article
Chemistry, Multidisciplinary
Satyajit Panda, Ram Singh Jat, Amir Fayaz, Jony Saha, Ramalingam Thirumoorthi, Tapta Kanchan Roy, M. Bhanuchandra
NEW JOURNAL OF CHEMISTRY
(2020)
Article
Chemistry, Multidisciplinary
Tanveer A. Khan, Kishalay Bhar, Ramalingam Thirumoorthi, Tapta Kanchan Roy, Anuj K. Sharma
NEW JOURNAL OF CHEMISTRY
(2020)