# 3.6. Descriptor "hybrid"

This descriptor hybridize multiple descriptors to form a new descriptor. For example we have a list of descriptor denoted by $$\mathcal D_1$$, $$\mathcal D_2$$, …, $$\mathcal D_N$$, the hybrid descriptor this the concatenation of the list, i.e. $$\mathcal D = (\mathcal D_1, \mathcal D_2, \cdots, \mathcal D_N)$$.

To use the descriptor in DeePMD-kit, one firstly set the type to hybrid, then provide the definitions of the descriptors by the items in the list,

        "descriptor" :{
"type": "hybrid",
"list" : [
{
"type" : "se_e2_a",
...
},
{
"type" : "se_e2_r",
...
}
]
},


A complete training input script of this example can be found in the directory

\$deepmd_source_dir/examples/water/hybrid/input.json