Ab Initio Quantum Chemistry

Introduction of Ab Initio Quantum Chemistry Ab initio quantum chemistry is computational chemistry based on quantum chemistry, and it uses physical quantity (electron mass, Plank constant, and electric quantity) and atomic coefficient to strictly calculate the whole integral of the molecule. Ab initio methods are developed based on Born-Oppenheimer, single electron, and non-relativistic approximation which are the solution of the Schrödinger equation without any empirical parameters. The popular methods are Hartree-Fock methods, Post-Hartree-Fock methods, and Monte Carlo methods. Due to its theoretical rigor and accuracy, ab initio methods can be used in small molecules, macromolecules, static properties, and dynamic properties. Scope of ApplicationsrnAb initio methods have been applied to the high precision calculation of small molecular systems, quantitative calculation of medium molecular systems, and qualitative calculation of large molecular systems. Molecular property predictionrnA diversity of molecular property including crystal structures, electronic bond structure, and lattice energy of molecular crystals can be calculated by ab initio methods. Multiple complex algorithms and high-quality database are available to support our prediction services. Apart from these, ab initio calculation of charge distribution, electrostatic potential, nonlinear optical properties, and thermochemical properties is attainable by our professional technical team. Materials properties predictionrnOur computational teams can calculate, predict or design material structures and properties through creating theoretical models with ab initio methods. At Alfa Chemistry, metal-organic framework structures, new polymorphs, more efficient semiconductor materials, superconductors, nuclear materials, and two-dimensional functional materials can be predicted by ab initio methods. Figure 1. Ab initio prediction of metal-organic framework structuresFigure 1. Ab initio prediction of metal-organic framework structures (Darby, J.P.; et al. 2020) Catalytic chemistryrnCatalytic reactions occupy a crucial position in chemistry. To find out the nature of chemical reactions, a wide range of experiments (such as possible intermediates, active catalysts, and routes) are tried one by one, which is energy-consuming and frequently of weak proof. To make up the experiments, ab initio methods based on the theoretical foundation can offer convincing information, such as photocatalytic reactions mechanisms, dominant transition states, and reactive intermediates. Biomedical researchrn1. Predictions of protein structures We can predict protein secondary structure and advanced structure according to the amino acid sequence of proteins using ab initio methods. Based on the results of the secondary structure, structural type and fold type prediction, our experts further assemble the secondary structure with high credibility and build the final protein structure combined with stereochemistry, hydrophilic and hydrophobic properties, hydrogen bonding, and electrostatic interactions. 2. Predictions of gene structures We establish the statistical model based on the structural characteristics of genes, and the gene structure is predicted only based on the gene sequences using ab initio methods. We adopt various ab initio prediction methods such as GENEMARK, GENSCAN, GENIE, HMMgene, GRAIL2, GeneParser, FGENEH, GeneKey, etc., to provide comprehensive prediction services.