What is the formula to calculating the lattice parameter or lattice constant of hexagonal structure in RHEED? How to sign the ZOLZ and FOLZ?

Why Austenite grains in steel show much more twinning than ferrite grains?

It is oftentimes said to be a distinctive metallographic trait that differentiates a fully austenitic and a fully felly ferritic steel without etching that might distinguish between two. Why...

02 March 2021 728 2 View

What could be the reason for not having further low chi square value (better agreement) in my refinement result?

I have tried every combination of parameter changes and after that i have a poor chi square value. I can't get it lower any further. I know there have been a lot of discussion about Rietveld...

26 February 2021 8,480 3 View

How to replicate the well conditions of a crystal hit with 20%(w/v) isopropanol?

I had a crystal hit in a well with 0.1M HEPEs pH 7.5, 10%(w/v) PEG 4000, and 20%(w/v) isopropanol. Why is isopropanol in w/v here if it's just solvent? How do I recreate this well condition?

25 February 2021 9,761 1 View

Is there a way to tell based on appearance which protein crystal should diffract the best?

I have had unheard of success with protein crystallography lately from a super successful protein expression and purification batch. I have attained a lately reproducible vast amount of crystals...

09 February 2021 5,155 5 View

Electron density difference maps(Fo-Fc): what is the meaning of negative densities (red blobs)?

Dear community, As far as I understand, negative density features point at stuff that is in the model, but not supported by experimental data. However, in many cases (e.g. attached image), when...

06 February 2021 2,847 2 View

Should the Ice 1h crystalline structure be lost during equilibration process in LAMMPS?

I have created an Ice 1h structure and am equilibrating it 100K in NVT ensemble in LAMMPS for a timestep of 0.25fs in 3000 steps. The potential used is TIP4P/Ice. Although the simulation runs fine...

26 January 2021 9,603 11 View

Is there any list that contains which stiffness/elastic modulus(Cii,Cij) effect which plane or direction of a cubic system in what way?

The value of stiffness/elastic modulus(Cii,Cjj) affects crystallographic planes in many ways like maximum shear or maximum tensile stress when stress is applied. The anisotropic materials show...

23 January 2021 2,877 2 View

Why can I not find all of my residues in model predicted by Swiss-Model?

I am trying to perform homology modeling using the swiss-model but I have found that the swiss-model gives the same number of residues as that of the template. Whereas my sequence has more...

21 January 2021 5,568 3 View

How will DeepMind AlphaFold2 solution of the core problem of protein structure prediction from sequence impact biology and biophysics?

AF2 may most strongly impact experimental determination of protein structure by multiple methods with possible benefits and negative impacts over time. Some areas may need to quickly pivot or...

13 December 2020 6,026 5 View

Modelling of proton disorder from SCXRD data?

Hi Is it possible to model a proton disorder from the single crystal X-ray diffraction data? We don't have access to neutron diffraction. #crystallography #SCXRD #refinement of structures Thanks

12 December 2020 9,507 3 View

Omar M S

Go to google search to find the formula or read the X-ray powder photography as the address attached

Alfiatur Rahmah

Thank you very much Mr. Umar. It will be beneficial for me

Anjan Bhukta

Dear Alfiatur Rahmah,

When you are observing the RHEED pattern due to passing of electron beam through the grown nanostructures (or thin film), its analysis is similar as the transmission electron diffraction in transmission electron microscope.

The distance of diffraction spots on the screen of any characteristic plane from the directly transmitted (000) spot, depends on the inter-planner spacing, wavelength, distance between specimen and screen. So you have to calibrate these parameters with the help of known samples.

Thereafter, for indexing to find out the crystallographic orientation, you can follow this paper.

Article Growth of Ag nanostructures on high-index Si (5 5 12) surfac...

Thanking you.

Anjan