NARloy-Z-D composites have relatively high thermal conductivities and are promising for further development. These results are consistent with the quantum mechanics-based model predictions. Elemental analysis showed migration of Zr to the NARloy-Z-D interface to form ZrC, which appeared to provide a low contact thermal resistance. On the other hand, D particles embedded in NARloy-Z matrix showed much improved thermal conductivity. Separately, the thermal conductivities of MWCNTs used in this work were measured, and the results showed very low values, a major factor in the low thermal conductivity of the composite. To eliminate the observed physical agglomeration, tangled multiwall MWCNTs were separated by acid treatment and electroless plated with a thin layer of chromium to keep them separated during further processing. The composites made form these powders showed lower thermal conductivity than the base NARloy-Z. Microstructural analysis showed that the MWCNTs, which were provided as tangles of MWCNTs by the manufacturer, did not detangle well during blending and formed clumps at the prior particle boundaries. In this study, NARloy-Z powder was blended with MWCNTs in a ball mill, and the resulting mixture was consolidated under high pressure and temperature using Field Assisted Sintering Technology (FAST). Quantum mechanics-based modeling showed that zirconium (Zr) in NARloy-Z should form ZrC at the MWCNT-Cu interface and provide a good thermal bond. % MWCNT finely dispersed in NARloy-Z matrix could nearly double the thermal conductivity, provided there is a good thermal bond between MWCNTs and copper matrix. The thermal conductivity of MWCNTs and D have been reported to be 5 to 10 times that of NARloy-Z. The approach was to embed high thermal conductivity multiwall carbon nanotubes (MWCNTs) and diamond (D) particles in the NARloy-Z matrix using powder metallurgy techniques. ".fftk_.-Multiwall Carbon Nanotubes and Copper-Diamond Composites for Advanced Rocket Engines This paper reports on the research effort to improve the thermal conductivity of the copper-based alloy NARloy-Z (Cu-3 wt.%Ag-0.5 wt.% Zr), the state-of-the-art alloy used to make combustion chamber liners in regeneratively-cooled liquid rocket engines, using nanotechnology. "::ForceFieldToolKit::GenZMatrix::genZmatrix" It works by identifying each atom in a molecule by a bond distance, bond angle and dihedral angle in relation to other atoms in the molecule. (procedure "::ForceFieldToolKit::GenZMatrix::genZmatrix" line 89) "::ForceFieldToolKit::GenZMatrix::writeZmat $acceptorAtom acceptor $Gnames $outfile" (procedure "::ForceFieldToolKit::GenZMatrix::writeZmat" line 167) The error says:Ītomselect: cannot parse selection text: index I believe the error is talking about the copper atom. What is the workaround at this FFTK step for new atoms that need to be Acceptor atoms? I am using VMD 1.9.4a12. It correctly writes Gaussian Input Files for my other Acceptor and Donor atoms without problems. The Gaussian Input File, CAI-ACC-Cu.gau, is blank. FFTK identifies my copper atom as an Acceptor atom, but can't write a Gaussian Input File for it. I have defined my own parameters based on copper CHARMM parameters from literature. I have atom type that is not in the CGENFF parameters, it is copper. I am running into an error in the water interaction FFTK step. On Thu, at 12:30 AM McGuire, Kelly > wrote: If you still have problems, you could send me the files (psf, pdb, par/str) and I could take a look. Subject: Re: vmd-l: FFTK Water Interactionīased on the error you report, the issue you experience is related to the bonds defined for the copper atoms (if any) in the psf file.įftk is trying to generate a zmatrix around the copper to orient the corresponding water molecules, but it does not found any bonds to set a frame of reference for the zmatrix.Ĭan you check the psf for bonds with the copper atom? For example, if this is a coordination complex, you might need to add explicitly the bonds to the copper atom. Out of curiosity, are nonbonded atoms (no specific scenario) always a problem with FFTK?ĭepartment of Physiology and Developmental Biology (Dihedral angles are the angles between an atom and the plane created by three other atoms.) This is done by using neighboring atoms to the atom you are describing. Explicit bonds are required and need to specified in the PSF. To identify atom 4 and all other atoms, you must include a bond length, bond angle and a dihedral angle. Reply: McGuire, Kelly: "Re: FFTK Water Interaction".Next in thread: McGuire, Kelly: "Re: FFTK Water Interaction".Maybe in reply to: mariano spivak: "Re: FFTK Water Interaction".Previous message: Tom Bartl: "Re: 32bit memory problems on Mac OS".Next message: John Stone: "Re: 32bit memory problems on Mac OS".
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