units
Differences
This shows you the differences between two versions of the page.
Next revisionBoth sides next revision | |||
units [2013/02/28 13:30] – created daniel | units [2013/03/01 08:25] – daniel | ||
---|---|---|---|
Line 1: | Line 1: | ||
- | '' | + | ====== Units ====== |
+ | ---- | ||
+ | //potfit// does not need a particular system of units. It can work with any system. The units used by //potfit// are implicitly defined in the configuration and potential files, and possibly by certain parameters specifying the potential. | ||
The reference configuration file contains atom positions, which implicitly defines a length unit. The interaction potential implicitly makes use of a length unit and an energy unit. Of course, this length unit must be the same as for the configuration file. The two units of length, and energy determine other units - like force and pressure - which are derived from them. The «temperature» in simulated annealing has the same dimension as the sum of squares - none at all. | The reference configuration file contains atom positions, which implicitly defines a length unit. The interaction potential implicitly makes use of a length unit and an energy unit. Of course, this length unit must be the same as for the configuration file. The two units of length, and energy determine other units - like force and pressure - which are derived from them. The «temperature» in simulated annealing has the same dimension as the sum of squares - none at all. | ||
- | ===== Example | + | == Example |
If the length unit is 1 Å = 1e-10 m, and the energy unit is 1 eV = 1.602e-19 J (which corresponds to 11594 K), then the unit of pressure is 160.2 GPa = 1602 kbar, and the unit of force is 1 eV/Å = 1.602e-9 N = 1.602 nN | If the length unit is 1 Å = 1e-10 m, and the energy unit is 1 eV = 1.602e-19 J (which corresponds to 11594 K), then the unit of pressure is 160.2 GPa = 1602 kbar, and the unit of force is 1 eV/Å = 1.602e-9 N = 1.602 nN | ||
units.txt · Last modified: 2018/01/05 10:07 by daniel