There is a simple and easy way to get the density of a crystal based on the CIF file containing the least possible information of a structure, i.e. chemical formula, lattice constants, space group, Z and atomic positions. Just upload the file on the IUCR checkcif site http://checkcif.iucr.org/index.html and check "Validation of CIF only (no structure factors)". Your calculated density Dx [g/cm^3] will be listed in the first part of the output results.

Diamond (Crystal Impact) provides the density. There is a free demo version (you can't save but you can easily import and visualize CIFs)

http://www.crystalimpact.com/diamond/Default.htm

Matteo, thank you very much for the kind and prompt response. I downloaded and tried the Diamond Demo version, it looks like a great software, thanks for pointing me to it. However I tried to open a CIF file of silicon, under the "data sheet", it shows cell volume of 160.16 Å3 , however below that, it is empty of "Calc. density" and "Meas. density"... does the program only read density from the CIF file? and if it's not included in the CIF file, can it calculate it? thanks much!

check that all atoms are properly specified in the atomic parameters window (expecially the oxidation value that must be explicitly given). If some atom is not correctly identified, then the density is not evaluated.

Platon Program http://www.cryst.chem.uu.nl/platon/

Easy: density(g/cm^3)=1.66*(molecular weight)*Z/(cell volume)

- molecular weight is given in the CIF line headed with (_chemical_formula_weight)

- Z in (_cell_formula_units_Z)

- cell volume in (_cell_volume)

So, you don't need a program, only a calculator!

Hi, you can try the CrystalMaker software, even in the demo version. The soft allows you to import CIF files, then you simply open the "Transform" menu and select "Calculate formula & density".

http://crystalmaker.com/crystalmaker/index.html

If you have a RES file (can be generated from the CIF) the program XPREP can calculate a matching HKL file (HKLF4 format).

In FullProf pack. You can Simulate a hole structure (I think pcr creator can load directly CIF files but i am not sure of this).

If not you create a normal .PCR file as if you were doing a Rietveld refinement but you run it on 'Simulated X-ray pattern (or whatever) and then in the .sum file must appear next to the head of the file. It call it density or volumic mass.

Why do you need a program? The CIF file already gives you the density of the crystal because thay provide: Z (number of unirt formula per unit cell), V (volumen of unit cell) and Molecular weight. With these parameter you can find the density

you may try our Mopro program, it computes the total electron density of a molecule.

it works for organic molecules;

There is a simple and easy way to get the density of a crystal based on the CIF file containing the least possible information of a structure, i.e. chemical formula, lattice constants, space group, Z and atomic positions. Just upload the file on the IUCR checkcif site http://checkcif.iucr.org/index.html and check "Validation of CIF only (no structure factors)". Your calculated density Dx [g/cm^3] will be listed in the first part of the output results.

There are perhaps many programs that calculated density but it should be also in the CIF file if the file is complete. If not it can be easily calculated as following:

d=1.66*Z*MW/V, where Z is number of formula unit in the cell, MW is the molecular weight of the formula unit (in a.m.u - atomic mass units) and V is unit cell volume in cubic angstroms. All Z, MW and V should be in the CIF already.

Hope it will help,

Peter Zavalij

Well, the problem seems to consist rather in "I am tweaking the lattice structure"... What programm do you use in relaxing the geometry? Most of all are capable to make a minimal comparision between the input data from experimental, I repeat, experimental CIF (RDX obtained cell parameteres, consequently the density, etc) and numerical optimization/simulation data obtained, cycle by cycle.

I know myself, and I tell you: experimental data are and must be of the most importance in concluding on the validity of other physical properties, obtained just through simulations...

Other potential problems: cell weigh density may be steady - but can appear modifications in cell parameters and symmetry... it is not acceptable, we trust in what experimentalists say (of course, there can be some large number of choices, regarding CIF files, for the same material - but with deviations in very resonable limits)... To make you more confuse, I didn't find yet what it means a "reasonable error limit", either between experimentalists, neither between their results and simulated ones... The conclusions, in simulations, always seem to sound like "in resonable / good / very good agreement with experimental".

It's not just OK, but mandatory to test your theoretical calculations with reality. If your software don't calculate, step by step, the geometrical transformations (by consequence, in density ones) - you'd better try an Excel formula.

Hope I didn't tell you stupid things, friendly,

Andy G.

Thank to all of you for the helpful comments! It will take me some time to fully digest all the information given above, but I'm sure I have got what I needed and greatly appreciate all of you for responding. PS: Gervais: that website is awesome, quickest and easiest way to do such check!

I intepreted the question as a feature request, so now my program CIF2Cell outputs the density. Downloadable from https://sourceforge.net/projects/cif2cell/ but beware that you first need to install PyCIFRW: https://sourceforge.net/projects/pycifrw.berlios/

But I agree with several answers that you probably don't need a special program to get the info, since CIF files typically list all the data you need, along with the experimentally determined density. But note that none of these things are in any way required to be in there.

All mentioned above about calculating the theoretical density of a crystal but how about calculating the theoretical density of amorphous material?

In a first approximation, the density of amorphous material can be assumed to be equal or slightly less then the crystalline state. For a better approximation, one needs more precise informations on the nature of the amorphous material. The following presentation gives more information on the subject

http://www.icdd.com/ppxrd/09/presentations/2010-ppxrd-Bates.pdf

than you G.Chapuis

i read the presentation you add but it isn't mention any information about calculating the density of amorphous alloy?

the purpose of the presentation was to show that amorphous materials do show some structure in the diffraction patterns which is close to powder patterns. Therefore we can assume that the density of such amorphous materials is close to the calculated ones of cristalline structures. Very often, amorphous materials are just cristalline materials with submicroscopic size leading to the extreme broadening of the Bragg peaks.

Yes i get it ,thank you

I partly agree with the last part of Gervais' answer.

It is true that the pattern of an amorphous material is very similar to the pattern of a nanocrystalline material if the short range order is the same (see e.g. the work of Le Bail et al using nano alpha-carnegieite to model silica glass). However saying that an amorphous is "just a crystalline material with submicroscopic size" is something that from the materials science point of view is incorrect.

Hi,

(although it is not connected to the original question) I thought we call a material "amorphous" when it displays no order resembling crystal lattice in its structure... and "nanocrystalline" if what? If it has 5nm, 10nm or 100nm average crystallite size? It always leads me to the opals, which are given as example for "amorphous" minerals, while if you look at it by HRTEM and SAED you ca define (usually) well developed crystals... of several nm or tens of nm. And if you interpret the XRD pattern of opals accordingly, than you have a good example for "nanocrystalline" material... or not? Then should I not call an "amorphous" material as non-crystalline , just to make it comparable to "nanocrystalline"?

I have nothing to add for the density side of the discussion :)

Regards

Ferenc, I think it just depends on the audience you are talking to. Your right 'amorphous' means a non-crystalline lattice. You can determine stoichiometry, but not phase of a material (ex. Fe2O3 and not a-Fe2O3, g-Fe2O3, etc.) Having said that grain boundaries are very small regions where there are 'breaks' in crystallinity. There are simple relations, assuming spherically shaped crystallites, that relates the increase of grain boundary volume to a reduction in grain size. If you are concerned about misrepresenting yourself, I'd just be more descriptive. For example, explain that the matrix of a material is amorphous, interspersed with small short range crystallographically ordered crystallites/grains. I would only feel comfortable describing a large, 3D bulk material as strictly amorphous if there was no long and short range order.

On the use of 'nanocrystalline', again I think the audience you are talking to makes a difference. Technically, 999nm is 'nanocrystalline.' But for those materials scientists that are trying to control the microstructure of a material to affect material properties, changes in material properties are not usually affected until you get down to 200nm or less. Then you start getting into mean free path lengths of phonons, charge carriers, photons; and 'critical size' for magnetism.