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Showing 1 to 20 of 52 for “"mp2"”.
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Monte Carlo explicitly correlated methods
… many-body perturbation theory, or the MC-MP2-F12 method, was developed for highly parallel evaluation of second-order many-body perturbation theory (MP2) energies near the complete basis set (CBS) limit. Single molecule energies were on average closer to the CBS limit than the …
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Embedded-fragment studies of ice, water, and molecular cluster cations
… ab initio second-order many-body perturbation (MP2) theory simulations of molecular liquids and solids with nonorthogonal lattice vectors. Three related anomalies of water ice Ih were investigated with BIM-MP2. The negative thermal expansion and pressure-induced amorphization of ice Ih were …
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Modeling of gas hydrates from first principles
… by the second-order Moller-Plesset method (MP2). However, a large basis set, cc-pVQZ, was found to be necessary in order to compute the binding energies to within 0.1 kcal/mol of the basis set limit. In order to sample accurately the PES, the H2O-CH4 energy of interaction was computed at …
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Genetic and Physiological Characterization of Clostridium Beijerinckii BA101 and NCIMB 8052
The addition of sodium acetate in MP2 medium was also able to stabilize solvent production by C. beijerinckii BA101, a hypersolvent producing mutant derived from NCIMB 8052. Moreover, BA101 demonstrated a greater increase in solvent production than NCIMB 8052 when acetate was added into MP2 medium. …
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Finite-Difference and Analytic-Gradient Approaches for Simulating Vibrational Circular Dichroism Using Second-Order Møller-Plesset Perturbation Theory and Configuration Interaction
… the second-order Møller-Plesset perturbation (MP2) theory and configuration interaction with double excitations (CID) electronic structure methods. Finally, we formulate an analytic implementation of the MP2 and configuration interaction including single and double excitations (CISD) AATs.
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Accurate Calculations of Molecular Properties with Explicitly Correlated Methods
… the computation of molecular properties with the MP2-F12 method, and its performance was assessed for prediction of the electric dipole and quadrupole moments of the BH, CO, H2O, and HF molecules (J. Zhang and E. F. Valeev, in preparation for submission). First, various MP2- F12 contributions to …
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Reaktive organische und anorganische Systeme mit Gruppe 14 Elementen: eine computerchemische Analyse
… 2-tert-Butylphenyl. Perturbation theory (MP2) is required to reproduce the geometrical features of cyclotriplumbanes Pb3R6 and shows good results for their chemical properties. Noticeable is the different hybridisation of the lead atoms with different substituents R. Calculations with …
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Explicitly Correlated Methods for Large Molecular Systems
… correlated second-order Mo ller-Plesset (MP2-F12) method in which all nontrivial post-mean-field steps are formulated with linear computational complexity in system size [Pavov{s}evi'c et al., {em J. Chem. Phys.} {bf 144}, 144109 (2016)]. The two key ideas are the use of pair-natural …
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Substituent Effects: A Computational Study on Stabilities of Cumulenes and Low Barrier Hydrogen Bonds
… theory (B3LYP, SVWN and BP86) and ab initio (HF, MP2) calculations at the 6-31G* basis set level. Using isodesmic reactions, correlation between stabilization energies of cumulenes and substituent group electronegativities (c BE) is established and the results from DFT and MP2 methods are compared …
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A theoretical study of molecular crystals
… by vibrational second-order Møller–Plesset (MP2) reproduced the observed frequencies correctly. In a three-dimensional framework of BIM, two configurations of solid hydrogen fluoride are explored. The en- ergies, equilibrium atomic positions, lattice constants, and dipole moments of the two …
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Experiment, thermodynamic properties and modeling on combustion of methyl tert-butyl ether : isobutane and isobutene and thermodynamic properties of chloro alkanes and alkenes
… are determined by ah initio Moller-Plesset (MP2(full)/6-31g(d)), complete basis set model chemistry (CBS-4 and CBS-q with MP2(full)/6-31g(d) and B3LYP/6-31g(d) optimized geometries), density functional (B3LYP/631g(d)), semi-empirical MOPAC (PM3) molecular orbital calculations, and by group …
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Large-Scale Applications of Multi-Reference Methods in Chemistry and Development of a Multi-Reference Moller-Plesset Perturbation Theory Program
… Moller-Plesset perturbation theory (MR-MP2) program, designed to perform large-scale computations, were developed and implemented. The MR-MP2 approach represents the most cost-effective multireference ansatz and requires an efficient evaluation of the Hamilton matrix for which an …
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Computational Studies of Protonated Cyclic Ethers and Benzylic Organolithium Compounds
… were performed at the B3LYP and MP2 levels (both with the 6-311++G** basis set). Structural analyses were performed for 10 protonated epoxides using B3LYP, MP2, and CCSD/6-311++G** calculations. Protonated 2-methyl-1,2-epoxypropane was the most problematic species studied, where …
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Mechanisms of Methoxide Ion Substitution and Acid- Catalyzed Z/E Isomerization of N-Methoxyimines
… eu for 2e. Ab initio calculations (HF/6-31+G*, MP2/6-31+G*//HF/6-31+G*, B3LYP/6- 31+G*//HF/6-31+G*, HF-SCIPCM/6-31+G*//HF/6-31+G*) were performed to define the reaction surface. These calculations demonstrate a relatively large barrier for nucleophilic attack in relation to halogen loss and …
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Theoretical Investigation of the Structure and Vibrational Frequencies of Water and Methanol Complexes
… structures have been optimized at the RHF and MP2 levels in various flexible basis sets and with the counterpoise correction for basis set superposition error, and trends in the structure and binding energies of several clusters are described. Good agreement wasobtained for the water dimer with …
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Advancements in Monte Carlo many body methods
… third-order Monte Carlo perturbation theory (MC-MP2 and MC-MP3) are two of the earliest MC-MB methods to have been developed. The algorithmic details of these methods are considered due to their relevance within the MC-MB family of methods. One significant methodological development for the MC-MP …
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Synthesis and properties of some electrolyte additives for lithium-ion batteries
… using Møller-Plesset Perturbation theory (MP2), the conformational preferences and energetics in vacuo were investigated using DFT calculations and the 6-31G(d,p) basis set. Subsequently, cyclic voltammetry and electrochemical impedance spectroscopy were used to characterize the compounds …
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An ab-initio study of bilayer graphene using higher order quantum chemical methods
… benzene dimer, shows excessive binding in the MP2 method while underbinding in the RPA method compared to accurate coupled cluster calculations84. It is expected that in an infinite system like bilayer graphene, the binding would be between the two. Moreover, RPA theory describes the dispersion …
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Evaluation of a knemometer
… each reading, called "measuring procedure 2" (MP2). Ten metal rods were measured at the start of each measuring day (314,90 - 449,90mm) to assess validity of the measurements. The mean standard deviation (SD) of the measurements performed on children was 0,4mm and the coefficient of variation …
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Theoretical studies of thermal syn elimination reactions
… optimized at the RHF/6-31G* level. In addition, MP2/6-31G* energies and RHF/6-31G* electrostatic potentials were calculated. Trends in calculated activation energies and electrostatic potentials agree with experimental results. It was determined that the C$\sb\alpha$-O bond appears to be breaking …
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