Nuclear stiffness, expressed as a hardness derivative, appears to be a good measure of the slope of global hardness. The authors analyze molecular states for which hardness has a maximum value. Maximum hardness principle (MHP) has been discussed. At the ground state hardness function does not obtain a maximum value versus spatial coordinates within a constant number of electrons (N), but is so ...

We study the computational complexity of decision and optimization problems that may be expressed as boolean contraint satisfaction problem with the global cardinality constraints. In this paper we establish a characterization theorem for the decision problems and derive approximation hardness results for the corresponding global optimization problems.

Under the QSPR/QSAR paradigm, a comparative study is made of the known drug activity of as many as 15 anti-tubercular drugs vis-à-vis the computed quantum mechanical global reactivity descriptors like global hardness, global softness and global electrophilicity index. The comparative study reveals that the experimentally determined activity of drug molecules, including its variation with side s...

Purpose: This paper presents an efficient and reliable swarm intelligence-based approach, namely particle swarm optimization [PSO] technique, to optimize the hardness and the parameters that affect the hardness in the Ni-Diamond composite coatings. Design/methodology/approach: Particle swarm optimizers are inherently distributed algorithms, in which the solution for a problem emerges from the i...

In formulating chemical-reactivity theory (CRT) so as to give it a deep foundation in density-functional theory (DFT), Parr, his collaborators, and subsequent workers have introduced reactivity indices as properties of isolated reactants, some of which are in apparent conflict with the underlying DFT. Indices which are first derivatives with respect to electron number are staircase functions of...

in this research, the interactions of hcn gas with pristine, ga-, n- and gan-doped of boron phosphide nanotube (bpnts) were investigated by using density function theory (dft). the structure, electrical and nqr parameters, quantum descriptors involving energy gap, global hardness, global softness, electrophilicity, electronic chemical potential and electronegativity were calculated. the adsorpt...

benzyl chloride and tin powder were used to prepare dibenzyltin dichloride according to a literatureprocedure. in this study, ir spectroscopy, homo-lumo energy gap, nbo analysis, polarizability,some geometrical parameters, natural charge and electrical potential of atoms, global hardness,electronic chemical potential, global electrophilicity index, and molar volume of dibenzyltindichloride were...

We study the problem of minimizing the number of guards positioned at a xed height h such that each triangle on a given 2.5-dimensional triangulated terrain T is completely visible from at least one guard. We prove this problem to be N P-hard, and we show that it cannot be approximated by a polynomial time algorithm within a ratio of (1 ?) 1 35 ln n for any > 0, unless N P T IM E(n O(log log n)...