The Crystal Cupboard in Virtual NanoLab provides simple access to over 500 predefined bulk crystal configurations. These configurations can either be used directly in calculations, or as templates for defining new crystal configurations.

With a few exceptions, the Crystal Cupboard uses Strukturberichts to categorize crystals. In the present version of Virtual NanoLab, only Strukturberichts without internal degrees of freedom are included. That means, that the positions of the atoms are fixed relative to the lattice vectors.

To be able to edit the lattice parameters (such as the c/a ratio for a tetragonal configuration) and the elements of the atoms in the basis, do either of the following

In either case, use the functionality of the Atomic Manipulator tool to edit the properties of the crystal.

You do not need to be familiar with the different Strukturberichts in order to use the tool. The list already includes all elemental crystals that belong to a supported Strukturbericht (for example, elemental fcc crystals such as gold or aluminum all belong to A1, and bcc crystals such as Cu belong to A2). In addition, the Crystal Cupboard contains a long range of the most common B-type Strukturberichts (diatomic crystals), such NaCl and CsCl structures.

You are not restricted to using crystals in the Crystal Cupboard only. If the crystal symmetry (specifically, the Strukturbericht) you are interested in is not included in the Crystal Cupboard, the crystal structure can be defined externally in a NanoLanguage script. The script file can then be dropped on any relevant VNL tool.

To filter (limit) the list of configurations in the Crystal Cupboard, you provide a number of search keywords in the Search field. The search is carried out as you type, and looks for the given keywords in the entire configuration definition (including comments). The search is defined as substring matching, except when the keyword is a single or two characters (such as “c” or “si”); these only match chemical elements. All keywords must match, except keywords prefixed by “-”, which instead are excluded. To clear the search field, click the Clear button.

Examples of searches:

Note that for many of the elements, the list includes also high-pressure as well as low- and high-temperature phases. When available, the standard phase, meaning the stable phase at atmospheric pressure and room temperature, is indicated in last column (this is only used for elemental crystals).

The primitive unit cell of the configuration selected in the list is displayed in the Preview window to the right. By right-clicking the preview window, it is possible to adjust the parameters of the atomic configuration plot (including repetition factors) just like in the Nanoscope. Note that the repetition factors are only used for the visualization; the crystal created by the tool only contains the atoms in the primitive cell.

The Crystal information box displays useful information and details about the crystal, such as its lattice parameters and space group, and a literature reference (if one is available). Some references are abbreviated; their full definition are given below:

Click the Save or Save As button to store the crystal configuration on your disk as a NanoLanguage script. In most cases, however, it usually makes more sense to use drag-and-drop directly from the Crystal Cupboard to another tool since you typically want to use the configuration to either set up a NanoLanguage script or to create electrodes for a two probe system. In either case, you don't need the configuration on the file system once you have it in the new tool.

References used in the Crystal Cupboard:

In cases where the lattice parameters are available from websites, the corresponding address to the main page of that site is also given. An invaluable and general reference for Strukturberichts is http://cst-www.nrl.navy.mil/lattice. Note, however, that the definitions of the lattice vectors sometimes differ between this reference and Virtual NanoLab. In some cases, this is due to corrected errors, but usually because the web site assigns the most convenient vectors for a given crystal, whereas Virtual NanoLab uses a standard convention for each of the 14 Bravais lattices.