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Ewald short-range part etc. 

Former-commit-id: 181d2da97f80dfcbe942d27819d831895a2df263
This commit is contained in:
Marek Nečada 2018-09-05 09:07:03 +03:00
parent f3a0ae6283
commit 858e997981
3 changed files with 90 additions and 20 deletions
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3
notes/ewald.lyx
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@ -3105,7 +3105,8 @@ Y_{n}^{m}\left(\frac{\pi}{2},\phi\right) & = & \left(-1\right)^{m}\sqrt{\frac{\l
\begin_inset Formula
\begin{eqnarray*}
\sigma_{n}^{m(1)} & = & -\frac{i^{n+1}}{2k^{2}\mathscr{A}}\left(-1\right)^{\left(n+m\right)/2}\sqrt{\left(2n+1\right)\left(n-m\right)!\left(n+m\right)!}\sum_{\vect K_{pq}\in\Lambda^{*}}^{'}\sum_{j=0}^{\left[\left(n-\left|m\right|/2\right)\right]}\frac{\left(-1\right)^{j}\left(\beta_{pq}/2k\right)^{n-2j}e^{im\phi_{\vect{\beta}_{pq}}}\Gamma_{j,pq}}{j!\left(\frac{1}{2}\left(n-m\right)-j\right)!\left(\frac{1}{2}\left(n+m\right)-j\right)!}\left(\frac{\gamma_{pq}}{2}\right)^{2j-1}\\
& = & -\frac{i^{n+1}}{2k^{2}\mathscr{A}}\sqrt{\pi}2^{n+1}\left(\left(n-m\right)/2\right)!\left(\left(n+m\right)/2\right)!Y_{n}^{m}\left(0,\phi_{\vect{\beta}_{pq}}\right)\sum_{\vect K_{pq}\in\Lambda^{*}}^{'}\sum_{j=0}^{\left[\left(n-\left|m\right|/2\right)\right]}\frac{\left(-1\right)^{j}\left(\beta_{pq}/2k\right)^{n-2j}\Gamma_{j,pq}}{j!\left(\frac{1}{2}\left(n-m\right)-j\right)!\left(\frac{1}{2}\left(n+m\right)-j\right)!}\left(\frac{\gamma_{pq}}{2}\right)^{2j-1},
& = & -\frac{i^{n+1}}{2k^{2}\mathscr{A}}\sqrt{\pi}2^{n+1}\left(\left(n-m\right)/2\right)!\left(\left(n+m\right)/2\right)!Y_{n}^{m}\left(0,\phi_{\vect{\beta}_{pq}}\right)\sum_{\vect K_{pq}\in\Lambda^{*}}^{'}\sum_{j=0}^{\left[\left(n-\left|m\right|/2\right)\right]}\frac{\left(-1\right)^{j}\left(\beta_{pq}/2k\right)^{n-2j}\Gamma_{j,pq}}{j!\left(\frac{1}{2}\left(n-m\right)-j\right)!\left(\frac{1}{2}\left(n+m\right)-j\right)!}\left(\frac{\gamma_{pq}}{2}\right)^{2j-1}\\
& = & -\frac{i^{n+1}}{k\mathscr{A}}\sqrt{\pi}2\left(\left(n-m\right)/2\right)!\left(\left(n+m\right)/2\right)!Y_{n}^{m}\left(0,\phi_{\vect{\beta}_{pq}}\right)\sum_{\vect K_{pq}\in\Lambda^{*}}^{'}\sum_{j=0}^{\left[\left(n-\left|m\right|/2\right)\right]}\frac{\left(-1\right)^{j}\left(\beta_{pq}/k\right)^{n-2j}\Gamma_{j,pq}}{j!\left(\frac{1}{2}\left(n-m\right)-j\right)!\left(\frac{1}{2}\left(n+m\right)-j\right)!}\left(\gamma_{pq}\right)^{2j-1},
\end{eqnarray*}
\end_inset

66
qpms/ewald.c
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@ -8,7 +8,6 @@
#include <gsl/gsl_integration.h>
#include <gsl/gsl_errno.h>
// parameters for the quadrature of integral in (4.6)
#ifndef INTEGRATION_WORKSPACE_LIMIT
#define INTEGRATION_WORKSPACE_LIMIT 30000
@ -22,6 +21,11 @@
#define INTEGRATION_EPSREL 1e-13
#endif
#ifndef M_SQRTPI
#define M_SQRTPI 1.7724538509055160272981674833411452
#endif
// sloppy implementation of factorial
static inline double factorial(const int n) {
assert(n >= 0);
@ -40,7 +44,21 @@ static inline double factorial(const int n) {
static inline complex double csq(complex double x) { return x * x; }
static inline double sq(double x) { return x * x; }
qpms_ewald32_constants_t *qpms_ewald32_constants_init(const qpms_l_t lMax)
typedef enum {
EWALD32_CONSTANTS_ORIG, // As in [1, (4,5)], NOT USED right now.
EWALD32_CONSTANTS_AGNOSTIC /* Not depending on the spherical harmonic sign/normalisation
* convention – the $e^{im\alpha_pq}$ term in [1,(4.5)] being
* replaced by the respective $Y_n^m(\pi/2,\alpha)$
* spherical harmonic. See notes/ewald.lyx.
*/
} ewald32_constants_option;
static const ewald32_constants_option type = EWALD32_CONSTANTS_AGNOSTIC;
qpms_ewald32_constants_t *qpms_ewald32_constants_init(const qpms_l_t lMax /*, const ewald32_constants_option type */,
const int csphase)
{
qpms_ewald32_constants_t *c = malloc(sizeof(qpms_ewald32_constants_t));
//if (c == NULL) return NULL; // Do I really want to do this?
@ -69,21 +87,40 @@ qpms_ewald32_constants_t *qpms_ewald32_constants_init(const qpms_l_t lMax)
c->s1_constfacs[y] = c->s1_constfacs_base + s1_constfacs_sz_cumsum;
// and here comes the actual calculation
for (qpms_l_t j = 0; j <= c->s1_jMaxes[y]; ++j){
switch(type) {
case EWALD32_CONSTANTS_ORIG: // NOT USED
c->s1_constfacs[y][j] = -0.5 * ipow(n+1) * min1pow((n+m)/2)
* sqrt((2*n + 1) * factorial(n-m) * factorial(n+m))
* min1pow(j) * pow(0.5, n-2*j)
/ (factorial(j) * factorial((n-m)/2-j) * factorial((n+m)/2-j))
* pow(0.5, 2*j-1);
break;
case EWALD32_CONSTANTS_AGNOSTIC:
c->s1_constfacs[y][j] = -2 * ipow(n+1) * M_SQRTPI
* factorial((n-m)/2) * factorial((n+m)/2)
* min1pow(j)
/ (factorial(j) * factorial((n-m)/2-j) * factorial((n+m)/2-j));
break;
default:
abort();
}
}
s1_constfacs_sz_cumsum += 1 + c->s1_jMaxes[y];
}
else
c->s1_constfacs[y] = NULL;
}
c->legendre0_csphase = csphase;
c->legendre0 = malloc(gsl_sf_legendre_array_n(lMax), sizeof(double));
if(GSL_SUCCESS != gsl_sf_legendre_array_e(GSL_SF_LEGENDRE_NONE, lMax, 0, c->legendre0))
abort();
return c;
}
void qpms_ewald32_constants_free(qpms_ewald32_constants_t *c) {
free(c->legendre0);
free(c->s1_constfacs);
free(c->s1_constfacs_base);
free(c->s1_jMaxes);
@ -149,7 +186,8 @@ int ewald32_sigma_long_shiftedpoints (
double jsum_err, jsum_err_c; kahaninit(&jsum_err, &jsum_err_c); // TODO do I really need to kahan sum errors?
for(qpms_l_t j = 0; j < (n-abs(m))/2; ++j) {
complex double summand = pow(rbeta_pq/k, n-2*j)
* e_imalpha_pq * cpow(gamma_pq, 2*j-1) // * Gamma_pq[j] bellow (GGG) after error computation
* e_imalpha_pq * c->legendre0[gsl_sf_legendre_array_index(n,abs(m))] // This line can actually go outside j-loop
* cpow(gamma_pq, 2*j-1) // * Gamma_pq[j] bellow (GGG) after error computation
* c->s1_constfacs[y][j];
if(err) {
// FIXME include also other errors than Gamma_pq's relative error
@ -244,21 +282,31 @@ int ewald32_sigma_short_shiftedpoints(
double Rpq_shifted_arg = atan2(Rpq_shifted.x, Rpq_shifted.y); // POINT-DEPENDENT
complex double e_beta_Rpq = cexp(I*cart2_dot(beta, Rpq_shifted)); // POINT-DEPENDENT
imaginary double prefacn = - I * pow(2./k, n+1) * M_2_SQRTPI / 2; // TODO put outside the R-loop and multiply in the end
for(qpms_l_t n = 1; n <= lMax; ++n) {
imaginary double prefacn = - I * pow(2./k, n+1) * M_2_SQRTPI / 2;
double R_pq_pown = pow(r_pq_shifted, n);
// TODO the integral here
double intres, interr;
int retval = ewald32_sr_integral(r_pq_shifted, k, n, eta,
&intres, &interr, workspace);
if (retval) abort();
//!!!!!!!!!!!!!!!!!!!!!! ZDE JSEM SKONČIL !!!!!!!!!!!!!!!!!!!!!!
// potřeba pořešit legendreovy funkce
for (qpms_m_t m = -n; m <= n; ++m){
if((m+n) % 2 != 0) // odd coefficients are zero.
continue; // nothing needed, already done by memset
complex double e_imf = cexp(I*m*Rpq_shifted_arg);
double leg = c->legendre0[gsl_sf_legendre_array_index(n, m)];
qpms_y_t y = qpms_mn2y(m,n);
if(err)
kahanadd(err + y, err_c + y, fabs(leg * (prefacn / I) * R_pq_pown
* interr)); // TODO include also other errors
ckahanadd(target + y, target_c + y,
prefacn * R_pq_pown * leg * intres * e_beta_Rpq * e_imf);
}
}
}
gsl_integration_workspace_free(workspace);
free(err_c);
if(err) free(err_c);
free(target_c);
return 0;
}

31
qpms/ewald.h
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@ -12,6 +12,18 @@
* Journal of Computational Physics 228 (2009) 1815–1829
*/
/*
* N.B.!!! currently, the long-range parts are calculated not according to [1,(4.5)], but rather
* according to the spherical-harmonic-normalisation-independent formulation in my notes
* notes/ewald.lyx.
* Both parts of lattice sums are then calculated with the P_n^|m| e^imf substituted in place
* of Y_n^m (this is quite a weird normalisation especially for negative |m|, but it is consistent
* with the current implementation of the translation coefficients in translations.c;
* in the long run, it might make more sense to replace it everywhere with normalised
* Legendre polynomials).
*/
/* Object holding the constant factors from [1, (4.5)] */
typedef struct {
qpms_l_t lMax;
@ -20,9 +32,18 @@ typedef struct {
complex double **s1_constfacs; // indices [y][j] where j is same as in [1, (4.5)]
// TODO probably normalisation and equatorial legendre polynomials should be included, too
complex double *s1_constfacs_base; // internal pointer holding the memory for the constants
double *legendre0; /* now with GSL_SF_LEGENDRE_NONE normalisation, because this is what is
* what the multipliers from translations.c count with.
*/
// gsl_sf_legendre_t legendre0_type;
int legendre0_csphase; /* 1 or -1; csphase of the Legendre polynomials saved in legendre0.
This is because I dont't actually consider this fixed in
translations.c */
} qpms_ewald32_constants_t;
qpms_ewald32_constants_t *qpms_ewald32_constants_init(qpms_l_t lMax);
qpms_ewald32_constants_t *qpms_ewald32_constants_init(qpms_l_t lMax, int csphase);
void qpms_ewald32_constants_free(qpms_ewald32_constants_t *);
@ -69,7 +90,7 @@ int ewald32_sigma_long_shiftedpoints_e (
point2d beta,
point2d particle_shift
);
int ewald32_sigma_long_points_and_shift (
int ewald32_sigma_long_points_and_shift (//NI
complex double *target_sigmalr_y, // must be c->nelem long
double *target_sigmalr_y_err, // must be c->nelem long or NULL
const qpms_ewald32_constants_t *c,
@ -78,7 +99,7 @@ int ewald32_sigma_long_points_and_shift (
point2d beta,
point2d particle_shift
);
int ewald32_sigma_long_shiftedpoints_rordered(
int ewald32_sigma_long_shiftedpoints_rordered(//NI
complex double *target_sigmalr_y, // must be c->nelem long
double *target_sigmalr_y_err, // must be c->nelem long or NULL
const qpms_ewald32_constants_t *c,
@ -95,7 +116,7 @@ int ewald32_sigma_short_shiftedpoints(
size_t npoints, const point2d *Rpoints_plus_particle_shift,
point2d particle_shift // used only in the very end to multiply it by the phase
);
int ewald32_sigma_short_points_and_shift(
int ewald32_sigma_short_points_and_shift(//NI
complex double *target_sigmasr_y, // must be c->nelem long
double *target_sigmasr_y_err, // must be c->nelem long or NULL
const qpms_ewald32_constants_t *c, // N.B. not too useful here
@ -103,7 +124,7 @@ int ewald32_sigma_short_points_and_shift(
size_t npoints, const point2d *Rpoints,
point2d particle_shift
);
int ewald32_sigma_short_points_rordered(
int ewald32_sigma_short_points_rordered(//NI
complex double *target_sigmasr_y, // must be c->nelem long
double *target_sigmasr_y_err, // must be c->nelem long or NULL
const qpms_ewald32_constants_t *c, // N.B. not too useful here