A theoretical synthesis of polymers by using uniform localization of molecular orbitals: Proposal of an elongation method

Abstract

A novel molecular orbital method for the calculations of polymer systems with local aperiodic part: The combination of the elongation method with the supercell method Local density of states of aperiodic polymers using the localized orbitals from an ab initio elongation methodThe elongation method, a new approach to calculating the electronic structure of polymers efficiently, is proposed as a model for real polymerization reactions following the normal chain reaction processes of initiation, propagation, and termination. The calculations are carried out by repeating the uniform localization o/wave/unctions with inclusion of the interaction between the end group of the cluster and an attacking molecule. As a first step of this treatment, the validity of our method is examined via application to regular and irregular model polymers consisting of hydrogen molecules at the extended Hiickellevel and comparing the results with those obtained from the conventional variational method. Furthermore, this treatment is performed on the real polymers such as polyethylene and polypropylene stereoisomers, and is proved to be reliable with advantages in computational time and storage. The approach is promising for application to very large systems on which direct variational calculations of the whole system are impossible. Moreover, it should be emphasized that this approach can mimic real reaction coordinates, or can be considered a theoretical synthesis of polymers.

A Festschrift in honor of Akira Imamura’s 77th birthday, his recent retirement, and his many contributions to theoretical chemistry

“…We are very pleased to be able to contribute to the research articles from our group, which will be published in the Imamura Festschrift Issue of Theoretical Chemistry Accounts in honor of Professor Imamura achievements to date. It has been now 20 years, since he proposed the elongation method in 1991 [1]. Thus, at Kyushu University, we now can conduct research based on elongation method owing to his very simple and very interesting idea-Theoretical Synthesis of Random Polymers (elongation method), and our thanks to him will never end.…”

Resist Investigation Method using <i>ab initio</i> MO Calculation on basis of Approximation Molecular Model

“…In spite of the ability, the first-principle calculation on resist material have rarely carried out due to complexity of resist polymer. If the resist simulation on a basis of the first-principle calculation such as the molecular orbital (MO) calculation [3] method is carried out, the resist development could be made a big progress to satisfy the specification. There are a lot of calculation methods which can optimize the chemical structure of organic polymer.…”

Density-fragment interaction approach for quantum-mechanical/molecular-mechanical calculations with application to the excited states of a Mg2+-sensitive dye

“…[34][35][36][37][38][39][40][41][42][43][44][45] There are also several approximate fragment approaches. 6,8,12,[46][47][48][49][50][51][52][53] In this paper, we propose a density-fragment interaction ͑DFI͒ approach for large-scale calculations based on a meanfield treatment of the electronic interaction between the fragments. In addition, the DFI scheme is combined with the QM/MM method, which we call the DFI-QM/MM method.…”

“…͑The van der Waals interactions are not included in the total QM/MM Fock or KS matrix, but into the total energy.͒ On the other hand, we have also seen significant development based on a fully QM description for large-scale calculations. [6][7][8][9][10][11][12][13][14][15][16][17][18] One of the authors ͑W.Y.͒ has developed the linear-scaling treatment, the divide-and-conquer ͑DC͒ method. [26][27][28] In this method, the entire system is first divided into several subsystems and their electron densities are calculated separately.…”

“…In this subject, many methods have been proposed so far. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] The most well-known and commonly used approach is the quantum-mechanical/molecularmechanical ͑QM/MM͒ method. [19][20][21][22] In this method, the electronically important part is described by quantum mechanics ͑QM͒, while the rest of the system is described by molecular mechanics ͑MM͒.…”