Results 191 to 200 of about 1,602 (228)
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A fragmentation and reassembly method forab initiophasing
Acta Crystallographica Section D Biological Crystallography, 2015Ab initiophasing withde novomodels has become a viable approach for structural solution from protein crystallographic diffraction data. This approach takes advantage of the known protein sequence information, predictsde novomodels and uses them for structure determination by molecular replacement.
Rojan, Shrestha, Kam Y J, Zhang
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[37] Patterson superposition and ab initio phasing
1997Publisher Summary This chapter presents the possibility of the ab initio solution of macromolecular structures, given two unusually favorable circumstances: the availability of very high-resolution data and the presence of one or more heavier atoms, such as transition metals or even sulfur.
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Photodissociation of Acetic Acid in the Gas Phase: An ab Initio Study
The Journal of Organic Chemistry, 2002Photodissociation of acetic acid in the gas phase was investigated using ab initio molecular orbital methods. The stationary structures on the ground-state potential energy surfaces were mainly optimized at the MP2 level of theory, while those on the excited-state surfaces were determined by complete active space SCF calculations with a correlation ...
Fang, WH +3 more
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Ab Initio Calculation of Phase Diagrams of Oxides
The Journal of Physical Chemistry B, 2001We show how Monte Carlo simulations with the explicit interchange of cations, the semigrand-canonical ensemble and configurational bias techniques, can be used to calculate phase diagrams for oxides, including both solid and liquid phases. We illustrate our approach with the system CaO/MgO where our techniques take full account of local structural ...
Lavrentiev, MY +3 more
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Ab-initio study of the Imma phase in silicon
Computational Materials Science, 2004We present an ab-initio study of the high-pressure phase transitions through the structure sequence β-tin → Imma → sh of silicon. The plane-wave pseudopotential approach to the density-functional theory within the generalized-gradient approximation implemented in VASP is used.
Katalin Gaal-Nagy, Dieter Strauch
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Ab Initio Calculations on Porphyrins in the Condensed Phase
MRS Proceedings, 1997AbstractPorphyrins are a promising class of materials for optical limiting applications, and in the condensed phase solvent effects have been shown to be significant. We report results with a method designed to simulate the effects of discrete solvent molecules, namely the effective fragment potential (EFP) approach which has been implemented for use ...
P.N. Day, Z. Wang, R. Pachter
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Structural phase transition of CdTe: an ab initio study
Journal of Molecular Modeling, 2012A constant pressure ab initio MD technique and density functional theory with a generalized gradient approximation (GGA) was used to study the pressure-induced phase transition in zinc-blende CdTe. We found that CdTe undergoes a structural first-order phase transition to [Formula: see text] (binary β-tin) tetragonal structure in the constant pressure ...
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On the ab initio phase determination by maximum entropy
Acta Crystallographica Section A Foundations of Crystallography, 1991In spite of some results reported recently, numerical and theoretical work still indicates that entropy alone is not, in general, a reliable figure of merit to select phases in the ab initio problem.
C. Lemaréchal, J. Navaza
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An ab Initio Study of Fructose in the Gas Phase
The Journal of Physical Chemistry A, 1999Seventy-two electronic structures of D-fructofuranose (D-FF) in the gas phase were determined by full geometry optimizations at the HF/6-31G* level. Twenty-nine structures, including the lowest energy species of nine distinct hydroxymethyl conformations of each anomer (R1-R9 and â1-â9), were selected for a detailed study of geometry, energy, atomic ...
Alice Chung-Phillips, Ying Ying Chen
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Ab initiostudies on high pressure phases of ice
Physical Review Letters, 1992The pressure-induced transition of ${\mathrm{H}}_{2}$O into the ice X phase, characterized by symmetric hydrogen bonding, is studied using ab initio molecular dynamics combined with ultrasoft pseudopotentials. A good description of the hydrogen bond is obtained only after gradient corrections to the local-density approximation are included.
Lee, Changyol +4 more
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