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Showing 1 to 15 of 15 for “"CASSCF"”.
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Machine-Learned Representations of Basis Sets and Their Application in Quantum Computational Chemistry
… expensive classical computations, such as CASSCF orbital optimization or ℓ1-norm minimization of the Hamiltonian. In this work, we introduce a general machine learning framework for fast basis set prediction in quantum computational chemistry. Our method employs an equivariant graph neural …
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Challenging systems for quantum chemistry : inorganic excited states and intermolecular aggregates
… of electron correlation systematically. A CASSCF/RASSCF study was performed for the most complex systems to be able to capture and analyse the multireference nature of the complexes. Later in the thesis the photochemistry arising from the photodissociaton of Mn2(CO)10 and Cr(CO)6 is …
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Vibrational Spectroscopy and Potential Energy Surface Analysis of the X˜ And B˜ States of Thiophosgene
… PES has also been fit, to a series of CASSCF ab initio calculations modeling the B˜(1 A1) state. Wavefunctions for both the X˜ (1A1) and B˜ (1A1) states were calculated in harmonic oscillator bases using the same normal coordinate representations. Along with an …
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The Electronic Excited States of Green Fluorescent Protein Chromophore Models
… state-averaged complete active space SCF (CASSCF) methods, time dependent density functional theory (TDDFT), equation-of motion coupled cluster (EOM-CCSD) and multireference perturbation theory (MRPT). Amongst the low-lying states we identify the optically bright pipi* state of the …
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(1) Artificial Synovial Fluid and Cartilage. (2) Non-Manumitative GD3+ Hosts as MRI Contrast Agents. (3) Five-Member Heterocycles as Switchable Ferromagnetic Coupling Units. (4) Liquid Crystal Opto-Optical Switch: Non-Destructive Information Retrieval Based on a Photochromic Fulgide as Trigger
… ranging from Be to O and from Mg to S at the CASSCF level with energy calculation at the MCQPDT2 level allowed for the discovery of four triplet ground state 2,5-dimethylene heterocycles. The series of 2,4-dimethylene heterocycles yields a family of acid-base driven magnetic switches in which …
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Theoretical and experimental investigation into the IR-VUV ion dip spectroscopy of amino acids and analogue systems
… of the spectroscopic results, including MP2 and CASSCF calculations. In IR-VUV ion dip spectroscopy, the isolated neutral molecules are ionized by a single photon of 10.5 eV energy 118 nm. If the neutral ground state amino acids are exposed to IR radiation prior to ionization, an IR spectrum can …
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Estudio de propiedades de compuestos de Au(I) y Au(III) con ligandos N-dadores
… se investiga experimental y teóricamente a nivel CASSCF/CASPT2 y DFT/TD-DFT la luminiscencia dual del ligando 4-(dimetilamino)piridina. Los resultados permiten validar el empleo de los cálculos DFT/TD-DFT para este tipo de análisis, lo que permite, a su vez, aplicarlos en el estudio de sistemas …
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Theoretical Studies on the ultrafast photodissociation of molecules
… Complete Active Space Self- Consistent Field (CASSCF) methods. Using a large active space allows us to include all of the states of interest within one calculation.
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The ground and excited state molecular structure of model systems undergoing photochemical processes and the characterization of active agents by means of vibrational spectroscopy and theoretical calculations
… Complete active space self consistent field (CASSCF) and configuration interaction (CI) calculations for some model systems were also performed to assess the experimental results on the excited state potential surfaces. The fundamentals of resonance Raman spectroscopy are treated in detail, …
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Quantum Nuclear Dynamics: Application to Spin-Forbidden Transitions and Lifetime of Vibrational States
… the complete active space self-consistent field (CASSCF) and density functional theory (DFT) methods is analyzed. The rate constants and the excited state lifetime obtained with the AIMS molecular dynamics and the nonadiabatic transition state theory are compared.
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Aplicação de métodos correlacionados de estrutura eletrônica ao estudo de estados excitados de moléculas em fase gasosa e em solução
… são efetuados com os métodos RHF, ROHF e CASSCF, utilizando-se várias funções de base
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Molecular Dynamics and Quantum Chemistry Studies of the Protein Bacteriorhodopsin
… are determined by means of the ab initio CASSCF method. The calculations account for the protein environment by explicitly including all protein partial atomic charges into the electronic Hamiltonian. The calculations are applied to an ensemble of bacteriorhodopsins generated by molecular …
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Multi-Configurational Investigation of Thermolytic Pathways of Highly Strained Ring Systems
The isomerization pathways of model high energy structures are of interest because of their relation to high energy density fuels. Electron resonance has been found to greatly affect the relative activation barriers for several isomerization pathways, and the major goal of this research is to …
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Singlet Oxygen Oxidation of Guanine, 9-Methylguanine and Guanine-Cytosine Base Pair: Dynamics and Kinetics Revealed by Parallel Gas- and Solution-Phase Experiments and Computations
… levels of theory, including Multi-referential CASSCF and CASMP2, were applied for a reliable description of the early-stage reaction potential surface (PES). The oxidation of protonated 9MG is initiated by the formation of a 5,8-endoperoxide <em>via</em> a concerted cycloaddition as protonated …
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Analyzing Electronic Correlation Effects in Molecules and Semiconductor Point Defects from First Principles Beyond Density Functional Theory
Transition-metal based molecules and point defects in wide-bandgap semiconductors have been of particular interest lately due to their potential quantum information science applications. To accurately calculate the electronic properties of these systems from first principles, it is important to …