20 KiB
Electrons
In conventional QMC simulations, up-spin and down-spin electrons are
different. The electron data structure contains the number of
up-spin and down-spin electrons, and the electron coordinates.
Context
The following data stored in the context:
uninitialized |
int32_t | Keeps bit set for uninitialized data |
num |
int64_t | Total number of electrons |
up_num |
int64_t | Number of up-spin electrons |
down_num |
int64_t | Number of down-spin electrons |
walk_num |
int64_t | Number of walkers |
provided |
bool | If true, electron is valid |
coord_new |
double[walk_num][3][num] | New set of electron coordinates |
coord_old |
double[walk_num][3][num] | Old set of electron coordinates |
coord_new_date |
uint64_t | Last modification date of the coordinates |
ee_distance |
double[walk_num][num][num] | Electron-electron distances |
ee_distance_date |
uint64_t | Last modification date of the electron-electron distances |
Data structure
typedef struct qmckl_electron_struct {
int64_t num;
int64_t up_num;
int64_t down_num;
int64_t walk_num;
int64_t coord_new_date;
int64_t ee_distance_date;
double* coord_new;
double* coord_old;
double* ee_distance;
int32_t uninitialized;
bool provided;
} qmckl_electron_struct;
The uninitialized integer contains one bit set to one for each
initialization function which has not bee called. It becomes equal
to zero after all initialization functions have been called. The
struct is then initialized and provided == true.
Access functions
When all the data relative to electrons have been set, the
following function returns true.
bool qmckl_electron_provided (const qmckl_context context);#+NAME:post
Initialization functions
To set the data relative to the electrons in the context, the
following functions need to be called. When the data structure is
initialized, the coord_new and coord_old arrays are both allocated.
qmckl_exit_code qmckl_set_electron_num (qmckl_context context, const int64_t up_num, const int64_t down_num);
qmckl_exit_code qmckl_set_electron_walk_num (qmckl_context context, const int64_t walk_num);
qmckl_exit_code qmckl_set_electron_coord (qmckl_context context, const double* coord);#+NAME:pre2
#+NAME:post2
To set the number of electrons, we give the number of up-spin and down-spin electrons to the context and we set the number of walkers.
The following function sets the electron coordinates of all the walkers. When this is done, the pointers to the old and new sets of coordinates are swapped, and the new coordinates are overwritten. This can be done only when the data relative to electrons have been set.
Test
/* Reference input data */
#define up_num ((int64_t) 3)
#define down_num ((int64_t) 2)
#define walk_num ((int64_t) 2)
#define num (up_num+down_num)
double coord[walk_num*3*num] =
{ 7.303633091022677881e+00, 1.375868694453235719e+01, 1.167371490471771217e-01,
4.547755371567960836e+00, 3.245907105524011182e+00, 2.410764357550297110e-01,
5.932816068137344523e+00, 1.491671465549257469e+01, 3.825374039119375236e-01,
7.347336142660052083e+00, 1.341946976062362129e+00, 1.648917914228352322e+00,
5.735221530102248444e+00, 1.064667491680036271e+01, 4.227201772236627297e-01,
8.099550978782254163e+00, 6.861498941099086757e+00, 4.015884841159429036e-02,
1.014757367558326173e+01, 5.219335322173662917e+00, 5.037004126899931322e-02,
1.484094322159507051e+01, 9.777903829455864226e+00, 5.243007994024882767e-02,
9.081723054990456845e+00, 5.499568496038920173e+00, 2.910446438899221347e-02,
2.583154239492383653e+00, 1.442282811294904432e+00, 6.387191629878670451e-02 };
/* --- */
qmckl_exit_code rc;
assert(!qmckl_electron_provided(context));
rc = qmckl_set_electron_num (context, up_num, down_num);
assert(rc == QMCKL_SUCCESS);
assert(!qmckl_electron_provided(context));
rc = qmckl_set_electron_walk_num (context, walk_num);
assert(rc == QMCKL_SUCCESS);
assert(qmckl_electron_provided(context));
rc = qmckl_set_electron_coord (context, coord);
assert(rc == QMCKL_SUCCESS);Computation
The computed data is stored in the context so that it can be reused by different kernels. To ensure that the data is valid, for each computed data the date of the context is stored when it is computed. To know if some data needs to be recomputed, we check if the date of the dependencies are more recent than the date of the data to compute. If it is the case, then the data is recomputed and the current date is stored.
Electron-electron distances
Get
qmckl_exit_code qmckl_get_electron_ee_distance(qmckl_context context, double* distance);Compute
| qmckl_context | context | in | Global state |
| int64_t | elec_num | in | Number of electrons |
| int64_t | walk_num | in | Number of walkers |
| double | coord[walk_num][3][elec_num] | in | Electron coordinates |
| double | ee_distance[walk_num][elec_num][elec_num] | out | Electron-electron distances |
integer function qmckl_compute_ee_distance_f(context, elec_num, walk_num, coord, ee_distance) &
result(info)
use qmckl
implicit none
integer(qmckl_context), intent(in) :: context
integer*8 , intent(in) :: elec_num
integer*8 , intent(in) :: walk_num
double precision , intent(in) :: coord(elec_num,3,walk_num)
double precision , intent(out) :: ee_distance(elec_num,elec_num,walk_num)
integer*8 :: k
info = QMCKL_SUCCESS
if (context == QMCKL_NULL_CONTEXT) then
info = QMCKL_INVALID_CONTEXT
return
endif
if (elec_num <= 0) then
info = QMCKL_INVALID_ARG_2
return
endif
if (walk_num <= 0) then
info = QMCKL_INVALID_ARG_3
return
endif
!$OMP PARALLEL DO DEFAULT(NONE) &
!$OMP SHARED(elec_num, walk_num, coord, ee_distance)
!$OMP PRIVATE(k)
do k=1,walk_num
info = qmckl_distance(context, 'T', 'T', elec_num, elec_num, &
coord(1,1,k), elec_num, &
coord(1,1,k), elec_num, &
ee_distance(1,1,k), elec_num)
end do
!$OMP END PARALLEL DO
end function qmckl_compute_ee_distance_fTest
/* Reference input data */
assert(qmckl_electron_provided(context));
double distance[walk_num*num*num];
rc = qmckl_get_electron_ee_distance(context, distance);
rc = qmckl_get_electron_ee_distance(context, distance);
assert(distance[0] == 0.);
assert(distance[1] == distance[num]);
assert(abs(distance[1]-8.6114953086801) < 1.e-12);