mirror of
https://github.com/TREX-CoE/trexio.git
synced 2024-08-25 06:31:43 +02:00
5.6 KiB
5.6 KiB
Examples
Accessing sparse quantities
Fortran
program print_energy
use trexio
implicit none
character*(128) :: filename ! Name of the input file
integer :: rc ! Return code for error checking
integer(8) :: f ! TREXIO file handle
character*(128) :: err_msg ! Error message
This program computes the energy as:
\[ E = E_{\text{NN}} + \sum_{ij} D_{ij}\, \langle i | h | j \rangle\, +\, \frac{1}{2} \sum_{ijkl} \Gamma_{ijkl}\, \langle i j | k l \rangle\; \textrm{ with } \; 0 < i,j,k,l \le n \]
One needs to read from the TREXIO file:
- $n$
- The number of molecular orbitals
- $E_{\text{NN}}$
- The nuclear repulsion energy
- $D_{ij}$
- The one-body reduced density matrix
- $\langle i |h| j \rangle$
- The one-electron Hamiltonian integrals
- $\Gamma_{ijkl}$
- The two-body reduced density matrix
- $\langle i j | k l \rangle$
- The electron repulsion integrals
integer :: n
double precision :: E, E_nn
double precision, allocatable :: D(:,:), h0(:,:)
double precision, allocatable :: G(:,:,:,:), W(:,:,:,:)
Declare Temporary variables
integer :: i, j, k, l, m
integer(8), parameter :: BUFSIZE = 10000_8
integer(8) :: offset, icount, size_max
integer :: buffer_index(4,BUFSIZE)
double precision :: buffer_values(BUFSIZE)
double precision, external :: ddot ! BLAS dot product
Obtain the name of the TREXIO file from the command line, and open it for reading
call getarg(1, filename)
f = trexio_open (filename, 'r', TREXIO_HDF5, rc)
if (rc /= TREXIO_SUCCESS) then
call trexio_string_of_error(rc, err_msg)
print *, 'Error opening TREXIO file: '//trim(err_msg)
stop
end if
Read the nuclear repulsion energy
rc = trexio_read_nucleus_repulsion(f, E_nn)
if (rc /= TREXIO_SUCCESS) then
call trexio_string_of_error(rc, err_msg)
print *, 'Error reading nuclear repulsion: '//trim(err_msg)
stop
end if
Read the number of molecular orbitals
rc = trexio_read_mo_num(f, n)
if (rc /= TREXIO_SUCCESS) then
call trexio_string_of_error(rc, err_msg)
print *, 'Error reading number of MOs: '//trim(err_msg)
stop
end if
Allocate memory
allocate( D(n,n), h0(n,n) )
allocate( G(n,n,n,n), W(n,n,n,n) )
Read one-electron quantities
rc = trexio_has_mo_1e_int_core_hamiltonian(f)
if (rc /= TREXIO_SUCCESS) then
stop 'No core hamiltonian in file'
end if
rc = trexio_read_mo_1e_int_core_hamiltonian(f, h0)
if (rc /= TREXIO_SUCCESS) then
call trexio_string_of_error(rc, err_msg)
print *, 'Error reading core Hamiltonian: '//trim(err_msg)
stop
end if
rc = trexio_has_rdm_1e(f)
if (rc /= TREXIO_SUCCESS) then
stop 'No 1e RDM in file'
end if
rc = trexio_read_rdm_1e(f, D)
if (rc /= TREXIO_SUCCESS) then
call trexio_string_of_error(rc, err_msg)
print *, 'Error reading one-body RDM: '//trim(err_msg)
stop
end if
Read two-electron quantities
rc = trexio_has_mo_2e_int_eri(f)
if (rc /= TREXIO_SUCCESS) then
stop 'No electron repulsion integrals in file'
end if
rc = trexio_read_mo_2e_int_eri_size (f, size_max)
if (rc /= TREXIO_SUCCESS) then
call trexio_string_of_error(rc, err_msg)
print *, 'Error reading number of ERIs: '//trim(err_msg)
stop
end if
W(:,:,:,:) = 0.d0
icount = BUFSIZE
offset = 0_8
do while (offset < size_max)
rc = trexio_read_mo_2e_int_eri(f, offset, icount, buffer_index, buffer_values)
if (rc /= TREXIO_SUCCESS) exit
do m=1,min(icount, size_max-offset)
i = buffer_index(1,m)
j = buffer_index(2,m)
k = buffer_index(3,m)
l = buffer_index(4,m)
W(i,j,k,l) = buffer_values(m)
W(k,j,i,l) = buffer_values(m)
W(i,l,k,j) = buffer_values(m)
W(k,l,i,j) = buffer_values(m)
W(j,i,l,k) = buffer_values(m)
W(j,k,l,i) = buffer_values(m)
W(l,i,j,k) = buffer_values(m)
W(l,k,j,i) = buffer_values(m)
end do
offset = offset + icount
end do
rc = trexio_has_rdm_2e(f)
if (rc /= TREXIO_SUCCESS) then
stop 'No two-body density matrix in file'
end if
rc = trexio_read_rdm_2e_size (f, size_max)
if (rc /= TREXIO_SUCCESS) then
call trexio_string_of_error(rc, err_msg)
print *, 'Error reading number of 2-RDM elements: '//trim(err_msg)
stop
end if
G(:,:,:,:) = 0.d0
icount = BUFSIZE
offset = 0_8
do while (offset < size_max)
rc = trexio_read_rdm_2e(f, offset, icount, buffer_index, buffer_values)
if (rc /= TREXIO_SUCCESS) exit
do m=1,min(icount, size_max-offset)
i = buffer_index(1,m)
j = buffer_index(2,m)
k = buffer_index(3,m)
l = buffer_index(4,m)
G(i,j,k,l) = buffer_values(m)
end do
offset = offset + icount
end do
Compute the energy
E = E_nn + &
ddot( n**2, D, 1, h0, 1 ) + &
0.5d0 * ddot( n**4, G, 1, W, 1 )
print *, 'Energy: ', E
Terminate
deallocate( D, h0, G, W )
end program