(PE-target)=
# PE
Receive total potential energy.



## <PE

Receive number of potential grid points

**Datatype:** `MDI_DOUBLE`  
**Quantity**: `1`  

 If the engine is at the [@DEFAULT](#@DEFAULT-target) node, it calculates and sends its total potential energy to the driver. 
If the engine has previously calculated the energy of the system, and no intervening commands from the driver could have changed the energy, 
the engine is permitted to send the previously calculated energy instead of recalculating it.

If the engine is not at the [@DEFAULT](#@DEFAULT-target) node, it sends its most recently calculated total potential energy to the driver.


### Examples


::::{tab-set}

:::{tab-item} Python
:sync: python

```python
import mdi

# connect to the engine
mdi_engine = mdi.MDI_Accept_Communicator()

# receive the total potential energy from the engine
mdi.MDI_Send_Command("<PE", mdi_engine)
pe = mdi.MDI_Recv(1, mdi.MDI_DOUBLE, mdi_engine)           

```
:::

:::{tab-item} C++
:sync: cpp

```cpp
#include "mdi.h"

// connect to the engine
MDI_Comm mdi_engine = MDI_Accept_Communicator();

// create a buffer to hold the total potential energy
double pe;

// receive the total potential energy from the engine
MDI_Send_Command("<PE", mdi_engine);
MDI_Recv(&pe, 1, MDI_DOUBLE, mdi_engine);   

```
:::

::::