Hello,
Sorry if this is a rather basic question, but my memories of solid-state chemistry are a bit rusty. Basically I'm trying to predict new crystal structures. I understand the crystallographic aspects quite well and know that at given external temperature and pressure the most stable...
Hello,
I'm a bit rusty with my fluid mechanics and can't seem to find the answer anywhere. Basically I have a pressure wave traveling in a liquid at the speed of sound through a pipe of the shape shown in the attachment (basically a semicircle of constant cross sectional area and then a cone of...
Hello,
I have a slightly awkward question: what if someone has a great new engineering/physics project which he thinks might work, however he needs a team of specialists in order to validate it and to assess its feasibility? I've heard that many universities have some kind of "technology...
I was reading about this problem: https://en.wikipedia.org/wiki/Flamant_solution
I think the second section "Forces acting on a half-plane" is particularly relevant :)
Let's assume I have a large block of crystalline diamond, with reported compressive strength of 110 GPa. If the cross-sectional area of the block is 1 m2, then obviously if I apply a force of 110x10^9 N the material will begin to fracture. But what if the pressure of 110 GPa is applied locally...
Thank you for you replies. I therefore understand that high-temperatures are not a pre-requisite for fusion to take place, high-pressures alone can be enough, but often high temperatures are a by-product of the high-pressure compression due to the way the fuel capsule behaves and its equation of...
Thanks for the answer. My supposition is that if we could get a larger sample to be compressed at the same pressure by applying a larger force, then we could apply the compression with parallel flat diamond plates rather than diamond tips which I believe fracture much more easily than the...
Hello, I'm trying to better understand the limiting factors in Diamond Anvil Cells that limit the achievable pressure to around 7 or 8 Mbar at the moment, despite not being a specialist. For example, is there a special reason other than the tiny size of the crystal sample used in DACs for why...
I know that to achieve fusion one has to satisfy the Lawson criterion. My question is: can fusion be achieved only by generating very high pressures but keeping the system at room temperature, or does it necessarily require a combination of both high pressures and high temperatures? If by some...
uhm the thing is that in DFT calculations (including entropy calculations using phonon vibrational frequencies) all the information about the space group is enclosed in the structure file like POSCAR file in the case of VASP. So if two space groups have exactly the same structure file as it is...
OK so I suppose that for a complex molecular crystal the difference between 210 and 227 will be apparent in the positions of the basis atoms, but not so for a simple monoatomic crystal like silicon...
So if I understand correctly for the purpose of computing the Gibbs Free energy of silicon...
Hello,
I was building some test crystal structures with VESTA software and I noticed when generating the POSCAR output files to be read by VASP that for a simple monoatomic basis such as in elemental silicon crystals some distinct space groups produce the same exact POSCAR files (i.e. same...
Hello,
I have a PhD in computational material science and experience using such computational techniques as Density Functional Theory and classical Molecular Dynamics. I would like to pursue a career in the private sector rather than in academia, however I found out the hard way that the...
Hello,
I would expect the heating of an elastic material upon sudden elastic compression to be given simply by the first law of thermodynamics, i.e. Delta Q=Delta U + P Delta V where P is constant since the compression is applied suddenly as in a square-wave pressure pulse (this is equivalent...