We investigate by first-principles molecular dynamics the structural properties of liquid GeSe 4 , i.e., Ge x Se 1Ϫx at xϭ0.2. This composition is very close to the so-called stiffness threshold composition, at which dramatic changes in a series of experimental properties occur. The calculated total neutron structure factor is in very good agreement with experiment. The results show that liquid GeSe 4 is a good prototype of a chemically ordered network. It consists of GeSe 4 tetrahedra that are connected by either shared Se atoms or Se chains.

A molecular-level understanding of why the addition of lithium salts to Organic Ionic Plastic Crystals (OIPCs) produces excellent ionic conductivity is described for the first time. These materials are promising electrolytes for safe, robust lithium batteries, and have been experimentally characterised in some detail. Here, molecular dynamics simulations demonstrate the effects of lithium ion doping on both the structure and dynamics of an OIPC matrix (tetramethylammonium dicyanamide [TMA][DCA]) and illustrate a molecular-level transport model: in the plastic crystal phase lithium ions can form clusters with [DCA](-), and this clustering then in turn creates free volume or defect paths in the remainder of the lattice, which enhances ion conduction.

We introduce a simple semiempirical anharmonic Kirkwood-Keating potential to model A x B 1−x C-type semiconductors. The potential consists of the Morse strain energy and Coulomb interaction terms. The optical constants of pure components, AB and BC, were employed to fit the potential parameters such as bond-stretching and -bending force constants, dimensionless anharmonicity parameter, and charges. We applied the potential to finite temperature molecular-dynamics simulations on Al x Ga 1−x As for which there is no lattice mismatch. The results were compared with experimental data and those of harmonic Kirkwood-Keating model and of equation-of-motion molecular-dynamics technique. Since the Morse strain potential effectively describes finite temperature damping, we have been able to numerically reproduce experimentally obtained optical properties such as dielectric functions and reflectance. This potential model can be readily generalized for strained alloys.

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We model lattice-mismatched group III-V semiconductor InxGa1-xAs alloys with the three-parameter anharmonic Kirkwood-Keating potential, which includes realistic distortion effect by introducing anharmonicity. Although the potential parameters were determined based on optical properties of the binary parent alloys InAs and GaAs, simulated dielectric functions, reflectance, and Raman spectra of alloys agree excellently with experimental data for any arbitrary atomic composition. For a wide range of atomic composition, InAs-and GaAs-bond retain their respective properties of binary parent crystals despite lattice and charge mismatch. It implies that use of the anharmonic Kirkwood-Keating potential may provide an optimal model system to investigate diverse and unique optical properties of quantum dot heterostructures by circumventing potential parameter searches for particular local structures.

e21138 Background: Alectinib is standard of care for metastatic anaplastic lymphoma kinase positive (ALK+) nonsmall cell lung cancer (NSCLC). Weight gain is an unexplored side effect reported in ~10%. To prevent or intervene alectinib-induced weight gain, more insight in its extent and etiology is needed. Methods: Change in body composition was analyzed in a prospective series of 46 patients with ALK+ NSCLC, treated with alectinib. Waist circumference, skeletal muscle (SM), visceral adipose tissue (VAT), and subcutaneous adipose tissue (SAT) were quantified using sliceOmatic software on computed tomography (CT) images at baseline, three months (3M) and one year (1Y). To investigate an exposure-toxicity relationship, alectinib plasma concentrations were quantified. Four patients with > 10 kg weight gain were referred to Erasmus MC Obesity Center for in-depth analysis (dietary habits, metabolic/endocrine assessment). Results: Mean increase in waist circumference was 9 cm (9.7%, p < 0.001) in 1Y with a 40% increase in abdominal obesity (p = 0.014). VAT increased 10.8 cm2 (15.0%, p = 0.003) in 3M and 35.7 cm2 (39.0%, p < 0.001) in 1Y. SAT increased 18.8 cm2 (12.4%, p < 0.001) in 3M and 45.4 cm2 (33.3%, p < 0.001) in 1Y. The incidence of sarcopenic obesity increased from 23.7% to 47.4% during 1Y of treatment. Baseline waist circumference was a positive predictor of increase in VAT (p = 0.037). No exposure-toxicity relationship was found. In-depth analysis showed increased appetite in two patients and metabolic syndrome in all four patients. Conclusions: Alectinib caused significant increased abdominal obesity, sarcopenic obesity, SAT and VAT quickly after initiation. This may lead to serious metabolic disturbances in long-surviving patients.[Table: see text]

In molecular-dynamics simulations for the long-range Coulomb interaction, a great deal of effort is devoted to reducing the computational complexity of the usual N2operations in the direct calculation. For bulk systems, we have designed a parallel algorithm based on the domain-decomposition strategy for the Ewald summation. The performance of the algorithm is evaluated on the in-house iPSC/860 system. We find that this algorithm reduces the computational complexity to O(N). For a 64,000-particle plasma in three dimension, the execution time on an 8-node system is 27.4 sec per MD time step. The interprocessor communication is a small fraction of the total execution time. We find linear speedups and a parallel efficiency of 0.85. For comparison, parallel algorithms are also designed for the Fast Multipole Method (FMM) - a divide and conquer scheme in which the system is divided into cubic subdomains and interactions between distant charged regions are calculated with a truncated multipole expansion. The performance of the FMM on Touchstone Delta machine is discussed.

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