# sc_TwoBodyTwoCenterDerivInt - Man Page

This is an abstract base type for classes that compute two centers integrals involving two electrons.

## Synopsis

`#include <tbint.h>`

Inherits **sc::RefCount**.

### Public Member Functions

int **nbasis** () const

Return the number of basis functions on center one.

int **nbasis1** () const

Return the number of basis functions on center one.

int **nbasis2** () const

Return the number of basis functions on center two.

int **nshell** () const

Return the number of shells on center one.

int **nshell1** () const

Return the number of shells on center one.

int **nshell2** () const

Return the number of shells on center two. **Ref**< **GaussianBasisSet** > **basis** ()

Return the basis set on center one. **Ref**< **GaussianBasisSet** > **basis1** ()

Return the basis set on center one. **Ref**< **GaussianBasisSet** > **basis2** ()

Return the basis set on center two.

const double * **buffer** () const

The computed shell integrals will be put in the buffer returned by this member.

virtual void **compute_shell** (int, int, **DerivCenters** &)=0

Given for shell indices, this will cause the integral buffer to be filled in.

virtual int **log2_shell_bound** (int=-1, int=-1)=0

Return log base 2 of the maximum magnitude of any integral in a shell block.

### Protected Member Functions

**TwoBodyTwoCenterDerivInt** (**Integral** *integral, const **Ref**< **GaussianBasisSet** > &b1, const **Ref**< **GaussianBasisSet** > &b2)

### Protected Attributes

**Integral** * **integral_****Ref**< **GaussianBasisSet** > **bs1_****Ref**< **GaussianBasisSet** > **bs2_**

double * **buffer_**

## Detailed Description

This is an abstract base type for classes that compute two centers integrals involving two electrons.

## Member Function Documentation

### virtual int sc::TwoBodyTwoCenterDerivInt::log2_shell_bound (int = -1, int = -1) [pure virtual]

Return log base 2 of the maximum magnitude of any integral in a shell block. An index of -1 for any argument indicates any shell.

## Author

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