Study elastic properties of the leucine and isoleuicine from first principles calculations.

I studied the elastic properties of crystalline L- and DL-forms of leucine and isoleucine within the framework of density functional theory with van der Waals interactions. The energy gaps of the considered crystals are 7.48-7.60 eV. Chiral molecules have the same chemical composition. Therefore, the study of crystalline amino acids provides a better understanding of how the structure of molecules affects mechanical properties of molecular crystals. Complete set of elastic constants for L-leucine, L-isoleucine, DL-leucine and DL-isoleucine were calculated. Linear compressibility of crystals has high anisotropy. The crystalline L- and DL-forms of leucine and isoleucine have different mechanical properties. Linear compressibility has a negative value for DL-isoleucine. My calculations predict that L-leucine and L-isoleucine are ductile compounds, while DL-leucine and DL-isoleucine are brittle compounds.

Study of the Elastic Properties of the Energetic Molecular Crystals Using Density Functionals with van der Waals Corrections.

We studied the elastic properties of crystalline energetic materials within the framework of density functional theory with van der Waals interactions (DFT-D3(BJ) and rev-vdW-DF2). The full sets of elastic constants were computed. The computed parameters are in good agreement with the experimental data. Among the crystals studied in this work, FOX7 had the lowest compressibility value of 0.0034 GPa-1 and had the highest anisotropy. Crystalline pentaerythritol tetranitrate had almost isotropic mechanical properties.

Hydrostatic Pressure Effects on Structural and Electronic Properties of ETN and PETN from First-Principles Calculations.

We studied the structural and electronic properties of pentaerythritol tetranitrate (PETN) and erythritol tetranitrate (ETN) crystals within the framework of density functional theory with van der Waals interactions. The computed lattice parameters have good agreement with experimental data. Electronic and structural properties of the crystals under 0-20 GPa hydrostatic pressure were studied. The parameters of equations of state calculated from the theoretical data show good agreement with experiment within the studied pressure intervals. We have also calculated the detonation velocity and pressure.

Electronic structure and chemical bond in naphthalene and anthracene.

We investigated the electronic structure of crystalline naphthalene and anthracene within the framework of density functional theory including van der Waals interactions (DFT-D). It is established that for better agreement with experimental values it is necessary to use the increased values of the van der Waals radii, which is caused by an overestimated value of the van der Waals interactions in crystalline linear oligoacenes. Utilization of the DFT-D leads to a correct account of the dispersion forces, which results in a high precision of the computed lattice parameters and cohesive energy. Based on the relaxed crystal structures, we have computed the total and deformation electron density and determined the mechanism of chemical bonds formation in crystals of naphthalene and anthracene. It has been established that the chemical bond in molecular crystals is formed under the influence of not only intramolecular but also intermolecular interactions. On the basis of the Mulliken population analysis it was revealed that two C(3) atoms in naphthalene (or C(3) and C(4) in anthracene) have a positive charge and the population of the rest of the carbon atoms increased, as compared with isolated molecule.

Atomic force microscopy detection of molecular complexes in multiprotein P450cam containing monooxygenase system.

The application of atomic force microscopy (AFM) technique in proteomic research, identification and visualization of individual molecules and molecular complexes within the P450cam containing monooxygenase system was demonstrated. The method distinguishes between the binary protein complexes and appropriate monomeric proteins and, also, between the binary and ternary complexes. The AFM images of the components of a cytochrome P450cam containing monooxygenase system - cytochrome P450cam (P450cam), putidaredoxin (Pd) and putidaredoxin reductase (PdR) - were obtained on a mica support. The molecules of P450cam, Pd and PdR were found to have typical heights of 2.6 +/- 0.3 nm, 2.0 +/- 0.3 and 2.8 +/- 0.3 nm, respectively. The measured heights of the binary Pd/PdR and P450cam/PdR complexes were 4.9 +/- 0.3 nm and 5.1 +/- 0.3 nm, respectively. The binary P450cam/Pd complexes were found to have a typical height of about (3.9 / 5.7 nm) and the ternary PdR/Pd/P450cam complexes, a typical height of about 9.1 +/- 0.3 nm.