(spinw-formula)=

# spinw.formula method

## Syntax
 
`formula = formula(obj)`
 
## Description
 
`result = formula(obj)` returns chemical mass, density, cellvolume etc.
of `obj`.
 
## Examples
 
The formula of the crystal stored in the
[https://raw.githubusercontent.com/SpinW/Models/master/cif/Ca2RuO4.cif](https://raw.githubusercontent.com/SpinW/Models/master/cif/Ca2RuO4.cif) linked file will be
printed onto the Command Window.
 
```matlab
cryst = spinw('https://raw.githubusercontent.com/SpinW/Models/master/cif/Ca2RuO4.cif')
cryst.formula
```
*Output*
```
     Chemical formula:  Ca2O4Ru1
     Formula mass:       245.224 g/mol
     Formula in cell:          4 units
     Cell volume:        355.397 ų
     Density:              4.583 g/cm³
```
 
 
## Name-Value Pair Arguments
 
`'obj'`
: [spinw](#spinw) object.
 
## Output Arguments
 
`formula` struct variable with the following fields:
* `m`         Mass of the unit cell in g/mol units.
* `V`         Calculated volume of the unit cell in length units (defined in [spinw.unit](#spinw-unit)).
* `rho`       Density in g/cm$^3$.
* `chemlabel` List of the different elements.
* `chemnum`   Number of the listed element names
* `chemform`  Chemical formula string.