The ab initio molecular orbital calculations (Gaussian 98) using a Hartree-Fock SCF method with a 6-31G basis set were carried out for 1, 2-bis (1-naphthalenecarboxy) ethane (1NP1N) as a flexible chain-linked molecule which formed an excimer to provide the most favorable orientation of the two chromophores. The results of the molecular orbital calculations suggest that the extended conformation is more favorable than the folded one. This result is in agreement with the experimental results of the fluorescence spectra.
A novel method to predict gas solubility in polymers by NPT-MD simulation was developed. It has beenimpossible to simulate a polymer film sandwiched between gas phase using a conventional NPT-MD method because of disappearance of the gas phase. Our idea is to fill gaseous space with virtual liquid in order to keep the volume of gas phase and to apply constant pressure. Using two phase model consisting of 1, 4-cis-polyisoprene film and gas phase filled with virtual liquid, we tried to estimate Henry's solubility coefficients of oxygen and carbon dioxide in 1, 4-cis-polyisoprene at 50°C and 100°C.The estimated results agreed with the experimental data.
Anisotropic motion within Human Lysozyme was compared between experiment and computer simulation. Thermal ellipsoids for Cα atoms were compared between the temperature factors from the X-ray crystallography and molecular dynamics simulation. The agreement between the experiment and the simulation was not good, however. Possible explanations for the disagreement are discussed.
In the development of new polymers, it is important to predict properties of polymers.But there are problems in existing methods to predict polymer properties. Molecular dynamics simulation takes long time and gives systematic error, and group contribution method requires endless correction terms to get exact values. Neural network has been applied to the prediction of glass transition temperatures of polymers. Network was trained by entering numbers of 12 kinds of bonds in monomer unit structures as input descriptors, and a leave-one-out test revealed that the network can well predict glass transition temperatures ranging above 600K with an average error of 29K.
The concept of our currently undergoing MICS project is presented. It is a system for constructing a kind of virtual society, called “virtual laboratory”. In the virtual world, participants can exchange information and can discuss it over the internet. The system can be constructed with Java and VRML technologies. Some tools which have already been implemented are also presented briefly.