# sc_R12IntsAcc man page

sc::R12IntsAcc — **R12IntsAcc** accumulates transformed (MO) integrals stored as (ijxy) where i, j, x, and, y lie in spaces I, J, **X**, and **Y**, respectively.

## Synopsis

`#include <r12ia.h>`

Inherits **sc::SavableState**.

Inherited by **sc::R12IntsAcc_MemoryGrp**, **sc::R12IntsAcc_MPIIOFile**, and **sc::R12IntsAcc_Node0File**.

### Public Types

enum **tbint_type** { **eri** =0, **r12** =1, **r12t1** =2, **r12t2** =3 }

Types of two-body operators that **R12IntsAcc** understands.

### Public Member Functions

**R12IntsAcc** (int **num_te_types**, int **ni**, int **nj**, int **nx**, int **ny**)**R12IntsAcc** (**StateIn** &)

void **save_data_state** (**StateOut** &)

Save the base classes (with save_data_state) and the members in the same order that the **StateIn** CTOR initializes them.

int **num_te_types** () const

The number of types of integrals that are being handled together.

int **ni** () const

Rank of index space i.

int **nj** () const

Rank of index space j.

int **nx** () const

Rank of index space x.

int **ny** () const

Rank of index space y.

size_t **blocksize** () const

Size of each block of the integrals of one type, in double words.

int **next_orbital** () const

The index of the first orbital in the next integrals batch to be stored.

virtual void **store_memorygrp** (**Ref**< **MemoryGrp** > &mem, int **ni**, const size_t blksize=0)=0

Stores all pair block of integrals held in mem in a layout assumed throughout **MBPT2_R12**.

virtual void **store_pair_block** (int i, int j, double *ints)=0

All member functions of this class and its children indices i and j don't include frozen orbitals Stores an ij pair block of integrals (assumes the block resides locally)

virtual void **commit** ()

Commit the content of the accumulator for reading.

bool **is_committed** ()

Has the content of the accumulator been commited for reading?

virtual void **activate** ()

Call before starting to read content.

virtual void **deactivate** ()

Call when done reading content.

const bool **is_active** ()

Check if can read content.

virtual double * **retrieve_pair_block** (int i, int j, **tbint_type** oper_type)=0

Retrieves an ij pair block of integrals.

virtual void **release_pair_block** (int i, int j, **tbint_type** oper_type)=0

Releases an ij pair block of integrals (if needed)

virtual bool **is_local** (int i, int j) const =0

Is this block stored locally?

virtual bool **is_avail** (int i, int j) const =0

Is this block available to this task?

virtual bool **has_access** (int proc) const =0

Does this task have access to all the integrals?

int **tasks_with_access** (vector< int > &twa_map) const

Returns the total number of tasks with access to integrals.

virtual bool **can_restart** () const =0

Can this specialization be used in restarts?

### Static Public Attributes

static const int **max_num_te_types_** = 4

### Protected Member Functions

virtual int **ntasks** () const =0

total number of tasks

virtual int **taskid** () const =0

ID of this task.

void **inc_next_orbital** (int **ni**)

The index of the first orbital in the next integrals batch to be stored.

### Protected Attributes

int **ni_**

int **nj_**

int **nx_**

int **ny_**

size_t **nxy_**

size_t **blksize_**

size_t **blocksize_**

int **next_orbital_**

bool **committed_**

bool **active_**

### Additional Inherited Members

## Detailed Description

**R12IntsAcc** accumulates transformed (MO) integrals stored as (ijxy) where i, j, x, and, y lie in spaces I, J, **X**, and **Y**, respectively.

ijxy is only the storage format, the actual type may be (ix|jy), (ij|xy), etc.

Transformed integrals are usually computed using a parallel MO integrals transformation procedure. In general, such transformations will require multiple passes through AO integrals. Each pass produces a batch of transformed integrals. For example, a batch in direct parallel MP2 energy algorithm is a set of integrals {(ix|jy)} in which i indices are in a finite subrange of O and x, j, and y take any of their allowed values. For example, if batch I contains all integrals (ix|jy) with i greater than or equal m but less than n, then batch I+1 contains integrals (ix|jy) with i greater than n. Integrals in batch 0 have indices i greater than or equal to 0.

After each pass the MO integrals are contained in a **MemoryGrp** object. The object is 'stored' in accumulator using `store_memorygrp(Ref<MemoryGrp>& mem, int ni)`

. After all batches have been stored, the content of **R12IntsAcc** needs to be 'committed' using **commit()**. After that blocks of MO integrals can be accessed using `retrieve_pair_block`

.

## Member Function Documentation

### void sc::R12IntsAcc::save_data_state (StateOut &) [virtual]

Save the base classes (with save_data_state) and the members in the same order that the **StateIn** CTOR initializes them. This must be implemented by the derived class if the class has data.

Reimplemented from **sc::SavableState**.

Reimplemented in **sc::R12IntsAcc_MPIIOFile_Ind**, **sc::R12IntsAcc_MPIIOFile**, **sc::R12IntsAcc_Node0File**, and **sc::R12IntsAcc_MemoryGrp**.

### virtual void sc::R12IntsAcc::store_memorygrp (Ref< MemoryGrp > & mem, int ni, const size_t blksize = 0) [pure virtual]

Stores all pair block of integrals held in mem in a layout assumed throughout **MBPT2_R12**. Let's suppose the number of tasks is nproc, nj is the number of j indices, ni is the number of i indices of integrals held in mem at the moment. Then all integrals with a given i and j are stored on task (i*nj+j)/nproc and this ij block is (i*nj+j)nproc -th block on this task. Each ij block contains num_te_types_ subblocks of integrals. Each subblock of integrals has blksize bytes allocated for it. Note that blksize may be larger than blksize_ because an ij-block of partially transformed integrals may be larger than the block of fully transformed integrals.

Implemented in **sc::R12IntsAcc_MPIIOFile_Ind**, **sc::R12IntsAcc_Node0File**, and **sc::R12IntsAcc_MemoryGrp**.

### int sc::R12IntsAcc::tasks_with_access (vector< int > & twa_map) const

Returns the total number of tasks with access to integrals. If task i has access to the integrals, then twa_map[i] is its index among the tasks with access, -1 otherwise.

## Author

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