(PE_NUC-target)=
# PE_NUC
Receive nuclear potential energy.



## <PE_NUC

Receive nuclear potential energy

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

 If the engine is at the [@DEFAULT](#@DEFAULT-target) node, it calculates and sends its nuclear potential energy to the driver. 
The nuclear potential energy is defined as including all interactions between the nuclei and any other particles or fields in the system, excluding any electrons. 
It also includes the interactions between the nuclei and themselves. 
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 nuclear 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 nuclear potential energy from the engine
mdi.MDI_Send_Command("<PE_NUC", mdi_engine)
pe_nuc = 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 nuclear potential energy
double pe_nuc;

// receive the nuclear potential energy from the engine
MDI_Send_Command("<PE_NUC", mdi_engine);
MDI_Recv(&pe_nuc, 1, MDI_DOUBLE, mdi_engine);

```
:::

::::