Messages

1

General Questions and Answers / Re: Can't run script in 2015

« on: December 15, 2015, 06:52 »

Ok, there were two machines, I deleted the second one (2015.1), but it still fails whenever I run a script.

And yes, it does say "fail." What I meant is there are no further details when I put the cursor over "failed."  It just says "local job executed with error,"

Edit: Nevermind, I got it to work. I just had to select the Local (2015.1) machine  .

2

General Questions and Answers / Can't run script in 2015

« on: December 10, 2015, 11:35 »

Whenever I try to run any script in 2015 version it fails. I attached the script to optimize the super cell like in the thin film tutorial. If I open the script I attached, send to job manager, save to a folder (automatically asks me to save), it fails. The log file is blank, there's no error message. I tried the script on one of the 2014 versions and it worked, but when I try in 2015 it fails instantly with no error message. 

3

General Questions and Answers / Re: Builder won't open for some reason.

« on: October 20, 2015, 10:29 »

I couldn't locate the project.ini file, but I just started a new project and the builder works fine now. 

And yes, I always backup my files.

4

General Questions and Answers / Builder won't open for some reason.

« on: October 17, 2015, 04:19 »

For some reason I can't bring up the builder, everything else seems to be working fine. I've been using the program on the same computer, it's a Linux system, but I haven't had this issue before now. I attached a screen shot of the error I get when I go to open the builder.

5

General Questions and Answers / Re: Mimicking decomposition of Silicon on 6H-SiC(000-1)

« on: September 15, 2015, 09:49 »

Thanks, I was trying to program a loop in py that could do this but it was using up a lot of time, I'm not familiar with all the functions and arguments.

Another question I have about the 6H-faces, the (0001) face is said to be the Si-face, and (000-1) is the C-face. The unit cell has the outer most atoms the other way around...?

6

General Questions and Answers / Mimicking decomposition of Silicon on 6H-SiC(000-1)

« on: September 13, 2015, 12:09 »

Edit: Sorry about all the misspellings and incoherent sentences on here previously. I may not have been awake when I started this topic; I was sleep typing. 

I was looking at this paper,

"Ogasawara N, Norimatsu W, Irle S, Kusunoki M. Growth mechanisms and selectivity for graphene or carbon nanotube formation on SiC (0001¯): A density-functional tight-binding molecular dynamics study. Chemical Physics Letters [serial online]. March 18, 2014;595-596:266-271. Available from: ScienceDirect, Ipswich, MA. Accessed September 12, 2015.

The author describes how the sublimation process for silicon on the 6H-SiC(000-1) surface was mimicked:

To mimic the decomposition process, we removed Si atoms one by one at intervals of 1.0 picoseconds (ps)...The removal order is also depicted in Figure 1 by way of circled numbers...

They don't go into any detail as to how they programmed it. I'm not sure how to pull that off without just doing simulation after simulation on each output successively after removing atoms one-by-one. Is there a straight forward way to do this that isn't as tedious? 
 

7

General Questions and Answers / Re: Building 6H-SiC Question

« on: September 12, 2015, 12:27 »

The bond stub is still there, so it looks as if the structure is still intact, only that the one silicon atom is outside the box. Try repeating the cell in A- and B-direction, or using Bulk Tools > Wrap to wrap the atoms inside the box, and check if the bonds still is broken.
I don't see any of these problems when I use the cif-file structure and do the same cleaving operations.

I think I may have been using an altered copy of the unit cell and didn't notice. It worked fine on a fresh copy

BTW. We'll soon have a brand new tutorial on vapor deposition simulations on the SiC(0001) surface..

Awesome, that's the topic of my senior research actually.

8

General Questions and Answers / Re: Building 6H-SiC Question

« on: September 11, 2015, 11:52 »

Ok, I see. Interestingly when I go to surface cleave the (0001) surface bonds break. I use the default setting for the surface lattice.

I've been reading,


Ogasawara N, Norimatsu W, Irle S, Kusunoki M. Growth mechanisms and selectivity for graphene or carbon nanotube formation on SiC (0001¯): A density-functional tight-binding molecular dynamics study. Chemical Physics Letters [serial online]. March 18, 2014;595-596:266-271. Available from: ScienceDirect, Ipswich, MA. Accessed September 11, 2015.

They use 5x5x.5 unit cells, I wonder if that is a coincidence?

Edit: sorry had to fix the images, now you can see what I mean, the first pic is just showing how I cleaved the surface in the 0001 direction on the carbon atom, the second shows the output with a broken bond right in the middle.

9

General Questions and Answers / Re: Building 6H-SiC Question

« on: September 11, 2015, 02:06 »

Thanks, that helped. It looks like the unit cell I was attempting to use was not twisted like yours is, and was actually a planar object. I'm undergraduate and have not taken solid state.

If you look at attachment "6H-SiC Unit Cell.png," that's the structure I repeated to obtain "6H SiC Example.png"

The "6H SiC Example.png" looks just like images of 6H-SiC that I find in literature sources. For instance, I've attached an excerpt from,

Jakse, N., Arifin, R., & Lai, S. K. (2011). Growth of graphene on 6H-SiC by molecular dynamics simulation. Condensed Matter Physics, 14(4), 43802-1-43802-7.

In the diagram the structure looks similar to " 6H SiC Example.png " in my original post. I'm guessing the structure in Jakse was not really meant to represent the physical appearance of the material from one face, but perhaps just a 2-d representation of the stacking sequence?

10

General Questions and Answers / Re: Building 6H-SiC Question

« on: September 10, 2015, 11:53 »

Another question I have about building the structures...I attached two excerpts from a paper, I don't see how they obtained that structure (i.e. what was the unit cell they repeated?) If I use the unit cell I described in my original post above (with 12 atoms), and repeat it, none of the surfaces appear similar to the figures below...

11

General Questions and Answers / Re: Building 6H-SiC Question

« on: September 10, 2015, 10:46 »

It looks right, but it's difficult to tell exactly just from the picture.
I have attached a .cif file of the SiC-6H (http://rruff.geo.arizona.edu/AMS/minerals/Moissanite) structure to which you can compare your structure.

I'm confused, doesn't 6H-SiC have 12 atoms in a unit cell? There's only 6 in the coordinates you gave for 6H.

Also, different sources seem to get different structures for the unit cell, is there more than one?

12

General Questions and Answers / EMTCalculator Parameters for Carbon?

« on: August 28, 2015, 04:26 »

If I go to use the ATK classical calculator it says "note EMTCalculator has no parameters for Carbon." But there is a citation for "Analytical potential for atomistic sumulations of silicon, carbon, and silicon carbide..." and in the script editor it's clearly using the Tersoff_SiC_2005 potential in the calculator block, and the literature reference show the parameters for carbon. So why does it say there are no parameters for carbon? I'm lost....

https://www.quantumwise.com/documents/manuals/latest/ReferenceManual/index.html/ref.tremolox.html


P.S. I neglected to say thanks for the help on my previous posts by the way, thanks!   

13

General Questions and Answers / Building 6H-SiC Question

« on: August 9, 2015, 18:31 »

My knowledge in solid state physics is limited. I'm trying to build 6H-SiC to run tests on the surfaces. I'm not sure if I'm doing this correctly. I start with the Hexagonal SiC in the data base, it consists of 4 atoms. I repeat it and then move atoms around to get the structure of the 6H-SiC unit cell (12 atoms) by going off schematics I've found from various sources. Then I repeat the 6H-SiC structure 5X5X1. I attached images of two of my stash items with the unit cell and the 5X5X1, I also attached two images I looked off of to help me.

Basically my question is...is this right?

14

General Questions and Answers / Re: Molecular Dynamics Bombardment Simulation (Contraint Editor???)

« on: June 4, 2015, 00:59 »

Thanks for your reply. I am still having difficulty giving the bombardment atom a velocity. There are two molecule blocks, the first one runs fine, I use all the parameters given in the tutorial. The second molecule block is tricky. For one, the version I'm using doesn't have the "velocity configuration" option under "initial velocity," there's only the "Maxwell-Boltzmann" option.

I also need to understand how to make the modifications to the script in the editor similar to that shown in the tutorial.

15

General Questions and Answers / Re: Molecular Dynamics Bombardment Simulation (Cohttp://quantuntraint Editor???)

« on: May 31, 2015, 00:47 »

Actually, it might be possible just to make modifications in the editor and put it in manually. I still don't see why the button isn't available in the script generator interface.