Electrons
Table of Contents
1 Context
The following data stored in the context:
uninitialized |
int32t | Keeps bit set for uninitialized data |
num |
int64t | Total number of electrons |
up_num |
int64t | Number of up-spin electrons |
down_num |
int64t | Number of down-spin electrons |
walk_num |
int64t | Number of walkers |
provided |
bool | If true, electron is valid |
coord_new |
double[walknum][3][num] | New set of electron coordinates |
coord_old |
double[walknum][3][num] | Old set of electron coordinates |
coord_new_date |
uint64t | Last modification date of the coordinates |
ee_distance |
double[walknum][num][num] | Electron-electron distances |
ee_distance_date |
uint64t | Last modification date of the electron-electron distances |
en_distance |
double[walknum][nuclnum][num] | Electron-nucleus distances |
en_distance_date |
uint64t | Last modification date of the electron-electron distances |
1.1 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; int64_t en_distance_date; double* coord_new; double* coord_old; double* ee_distance; double* en_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.
When all the data relative to electrons have been set, the
following function returns true.
bool qmckl_electron_provided (const qmckl_context context);
1.2 Access functions
Access functions return QMCKL_SUCCESS when the data has been
successfully retrieved. It returnes QMCKL_INVALID_CONTEXT when
the context is not a valid context, and QMCKL_NOT_PROVIDED when
the data has not been provided. If the function returns
successfully, the variable pointed by the pointer given in argument
contains the requested data. Otherwise, this variable is untouched.
1.2.1 Number of electrons
1.2.2 Number of walkers
A walker is a set of electron coordinates that are arguments of
the wave function. walk_num is the number of walkers.
1.2.3 Electron coordinates
Returns the current electron coordinates. The pointer is assumed
to point on a memory block of size 3 * elec_num * walk_num.
The normal order of the indices is:
| Normal | Transposed | |
|---|---|---|
| C | [walk_num][elec_num][3] |
[walk_num][3][elec_num] |
| Fortran | (3,elec_num,walk_num) |
(elec_num,3,walk_num) |
1.3 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 internal 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 char transp, const double* coord);
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.
Important: changing the electron coordinates increments the date in the context.
1.4 Test
/* Reference input data */ int64_t walk_num = chbrclf_walk_num; int64_t elec_num = chbrclf_elec_num; int64_t elec_up_num = chbrclf_elec_up_num; int64_t elec_dn_num = chbrclf_elec_dn_num; double* elec_coord = &(chbrclf_elec_coord[0][0][0]); int64_t nucl_num = chbrclf_nucl_num; double* charge = chbrclf_charge; double* nucl_coord = &(chbrclf_nucl_coord[0][0]); /* --- */ qmckl_exit_code rc; assert(!qmckl_electron_provided(context)); int64_t n; rc = qmckl_get_electron_num (context, &n); assert(rc == QMCKL_NOT_PROVIDED); rc = qmckl_get_electron_up_num (context, &n); assert(rc == QMCKL_NOT_PROVIDED); rc = qmckl_get_electron_down_num (context, &n); assert(rc == QMCKL_NOT_PROVIDED); rc = qmckl_set_electron_num (context, elec_up_num, elec_dn_num); assert(rc == QMCKL_SUCCESS); assert(!qmckl_electron_provided(context)); rc = qmckl_get_electron_up_num (context, &n); assert(rc == QMCKL_SUCCESS); assert(n == elec_up_num); rc = qmckl_get_electron_down_num (context, &n); assert(rc == QMCKL_SUCCESS); assert(n == elec_dn_num); rc = qmckl_get_electron_num (context, &n); assert(rc == QMCKL_SUCCESS); assert(n == elec_num); int64_t w; rc = qmckl_get_electron_walk_num (context, &w); assert(rc == QMCKL_NOT_PROVIDED); rc = qmckl_set_electron_walk_num (context, walk_num); assert(rc == QMCKL_SUCCESS); rc = qmckl_get_electron_walk_num (context, &w); assert(rc == QMCKL_SUCCESS); assert(w == walk_num); assert(qmckl_electron_provided(context)); rc = qmckl_set_electron_coord (context, 'N', elec_coord); assert(rc == QMCKL_SUCCESS); double elec_coord2[walk_num*3*elec_num]; rc = qmckl_get_electron_coord (context, 'N', elec_coord2); assert(rc == QMCKL_SUCCESS); for (int64_t i=0 ; i<3*elec_num ; ++i) { assert( elec_coord[i] == elec_coord2[i] ); }
2 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.
2.1 Electron-electron distances
2.1.1 Get
qmckl_exit_code qmckl_get_electron_ee_distance(qmckl_context context, double* const distance);
2.1.2 Compute
| qmcklcontext | context | in | Global state |
| int64t | elecnum | in | Number of electrons |
| int64t | walknum | in | Number of walkers |
| double | coord[walknum][3][elecnum] | in | Electron coordinates |
| double | eedistance[walknum][elecnum][elecnum] | 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 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) if (info /= QMCKL_SUCCESS) then exit endif end do end function qmckl_compute_ee_distance_f
2.1.3 Test
assert(qmckl_electron_provided(context)); double ee_distance[walk_num * elec_num * elec_num]; rc = qmckl_get_electron_ee_distance(context, ee_distance); // (e1,e2,w) // (0,0,0) == 0. assert(ee_distance[0] == 0.); // (1,0,0) == (0,1,0) assert(ee_distance[1] == ee_distance[elec_num]); // value of (1,0,0) assert(fabs(ee_distance[1]-7.152322512964209) < 1.e-12); // (0,0,1) == 0. assert(ee_distance[elec_num*elec_num] == 0.); // (1,0,1) == (0,1,1) assert(ee_distance[elec_num*elec_num+1] == ee_distance[elec_num*elec_num+elec_num]); // value of (1,0,1) assert(fabs(ee_distance[elec_num*elec_num+1]-6.5517646321055665) < 1.e-12);
2.2 Electron-nucleus distances
2.2.1 Get
qmckl_exit_code qmckl_get_electron_en_distance(qmckl_context context, double* distance);
2.2.2 Compute
| qmcklcontext | context | in | Global state |
| int64t | elecnum | in | Number of electrons |
| int64t | nuclnum | in | Number of nuclei |
| int64t | walknum | in | Number of walkers |
| double | eleccoord[walknum][3][elecnum] | in | Electron coordinates |
| double | nuclcoord[3][elecnum] | in | Nuclear coordinates |
| double | endistance[walknum][nuclnum][elecnum] | out | Electron-nucleus distances |
integer function qmckl_compute_en_distance_f(context, elec_num, nucl_num, walk_num, elec_coord, nucl_coord, en_distance) & result(info) use qmckl implicit none integer(qmckl_context), intent(in) :: context integer*8 , intent(in) :: elec_num integer*8 , intent(in) :: nucl_num integer*8 , intent(in) :: walk_num double precision , intent(in) :: elec_coord(elec_num,3,walk_num) double precision , intent(in) :: nucl_coord(nucl_num,3) double precision , intent(out) :: en_distance(elec_num,nucl_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 (nucl_num <= 0) then info = QMCKL_INVALID_ARG_3 return endif if (walk_num <= 0) then info = QMCKL_INVALID_ARG_4 return endif do k=1,walk_num info = qmckl_distance(context, 'T', 'T', elec_num, nucl_num, & elec_coord(1,1,k), elec_num, & nucl_coord, nucl_num, & en_distance(1,1,k), elec_num) if (info /= QMCKL_SUCCESS) then exit endif end do end function qmckl_compute_en_distance_f
2.2.3 Test
assert(!qmckl_nucleus_provided(context)); assert(qmckl_electron_provided(context)); rc = qmckl_set_nucleus_num (context, nucl_num); assert(rc == QMCKL_SUCCESS); rc = qmckl_set_nucleus_charge (context, charge); assert (rc == QMCKL_SUCCESS); rc = qmckl_set_nucleus_coord (context, 'T', nucl_coord); assert (rc == QMCKL_SUCCESS); assert(qmckl_nucleus_provided(context)); double en_distance[walk_num][nucl_num][elec_num]; rc = qmckl_get_electron_en_distance(context, &(en_distance[0][0][0])); assert (rc == QMCKL_SUCCESS); // (e,n,w) in Fortran notation // (1,1,1) assert(fabs(en_distance[0][0][0] - 7.546738741619978) < 1.e-12); // (1,2,1) assert(fabs(en_distance[0][1][0] - 8.77102435246984) < 1.e-12); // (2,1,1) assert(fabs(en_distance[0][0][1] - 3.698922010513608) < 1.e-12); // (1,1,2) assert(fabs(en_distance[1][0][0] - 5.824059436060509) < 1.e-12); // (1,2,2) assert(fabs(en_distance[1][1][0] - 7.080482110317645) < 1.e-12); // (2,1,2) assert(fabs(en_distance[1][0][1] - 3.1804527583077356) < 1.e-12);