nnp::KspaceGrid Class Reference

#include <Kspace.h>

Collaboration diagram for nnp::KspaceGrid:

Public Member Functions
	KspaceGrid ()
	Constructor.
void	setup (Vec3D box[3], EwaldSetup &ewaldSetup)
	Set up reciprocal box vectors and eta.

Public Attributes
KSPACESolver	kspaceSolver
	Method for calculating the reciprocal part.
double	eta
	Ewald summation eta parameter.
double	kCut
	Cutoff in reciprocal space.
double	rCut
	Cutoff in real space.
double	volume
	Volume of real box.
double	pre
	Ewald sum prefactor \(\frac{2\pi}{V}\).
int	n [3]
	Required box copies in each box vector direction.
Vec3D	kbox [3]
	Reciprocal box vectors.
std::vector< Kvector >	kvectors
	Vector containing all k-vectors.

Private Member Functions
void	calculatePbcCopies (double cutoffRadius)
	Compute box copies in each direction.

Detailed Description

Definition at line 50 of file Kspace.h.

Constructor & Destructor Documentation

KspaceGrid()

KspaceGrid::KspaceGrid

(

)

Constructor.

Definition at line 38 of file Kspace.cpp.

                       : eta   (0.0),
                           kCut  (0.0),
                           volume(0.0),
                           pre   (0.0)
{
}

References eta, kCut, pre, and volume.

Member Function Documentation

setup()

void KspaceGrid::setup	(	Vec3D	box[3],
		EwaldSetup &	ewaldSetup )

Set up reciprocal box vectors and eta.

Parameters

[in]	box	Real box vectors.
[in]	ewaldSetup	Settings of ewald summation.

Definition at line 45 of file Kspace.cpp.

{
    volume = fabs(box[0] * (box[1].cross(box[2])));
    pre = 2.0 * M_PI / volume;
 
    kbox[0] = pre * box[1].cross(box[2]);
    kbox[1] = pre * box[2].cross(box[0]);
    kbox[2] = pre * box[0].cross(box[1]);
 
    eta = ewaldSetup.params.eta;
    kCut = ewaldSetup.params.kCut;
 
    // Compute box copies required in each direction.
    calculatePbcCopies(kCut);
 
    double halfSphere = 1; // TODO
    if (halfSphere)
    {
        // Compute k-grid (only half sphere because of symmetry).
        for (int i = 0; i <= n[0]; ++i)
        {
            int sj = -n[1];
            if (i == 0) sj = 0;
            for (int j = sj; j <= n[1]; ++j)
            {
                int sk = -n[2];
                if (i == 0 && j == 0) sk = 0;
                for (int k = sk; k <= n[2]; ++k)
                {
                    if (i == 0 && j == 0 && k == 0) continue;
                    Vec3D kv = i * kbox[0] + j * kbox[1] + k * kbox[2];
                    double knorm2 = kv.norm2();
                    if (kv.norm2() < kCut * kCut)
                    {
                        //fprintf(stderr, "sqk = %24.16E\n", kv.norm());
                        kvectors.push_back(kv);
                        kvectors.back().knorm2 = knorm2; // TODO: Necessary?
                        kvectors.back().coeff = exp(-0.5 * eta * eta * knorm2)
                                              * 2.0 * pre / knorm2;
                    }
                }
            }
        }
    }
    else
    {
        // Compute full k-grid.
        for (int i = -n[0]; i <= n[0]; ++i)
        {
            for (int j = -n[1]; j <= n[1]; ++j)
            {
                for (int k = -n[2]; k <= n[2]; ++k)
                {
                    if (i == 0 && j == 0 && k == 0) continue;
                    Vec3D kv = i * kbox[0] + j * kbox[1] + k * kbox[2];
                    double knorm2 = kv.norm2();
                    if (kv.norm2() < kCut * kCut)
                    {
                        kvectors.push_back(kv);
                        kvectors.back().knorm2 = knorm2; // TODO: Necessary?
                        kvectors.back().coeff = exp(-0.5 * eta * eta * knorm2)
                                              * 2.0 * pre / knorm2;
                    }
                }
            }
        }
    }
}

References calculatePbcCopies(), nnp::Vec3D::cross(), nnp::EwaldParameters::eta, eta, kbox, nnp::EwaldParameters::kCut, kCut, kvectors, n, nnp::Vec3D::norm2(), nnp::EwaldSetup::params, pre, and volume.

Referenced by nnp::Structure::calculateDAdrQ(), and nnp::Structure::calculateElectrostaticEnergy().

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calculatePbcCopies()

void KspaceGrid::calculatePbcCopies ( double cutoffRadius )

private

Compute box copies in each direction.

Parameters

[in]

cutoffRadius

Cutoff radius.

TODO: This is code copy from Structure class!

Definition at line 114 of file Kspace.cpp.

{
    Vec3D axb;
    Vec3D axc;
    Vec3D bxc;
 
    axb = kbox[0].cross(kbox[1]).normalize();
    axc = kbox[0].cross(kbox[2]).normalize();
    bxc = kbox[1].cross(kbox[2]).normalize();
 
    double proja = fabs(kbox[0] * bxc);
    double projb = fabs(kbox[1] * axc);
    double projc = fabs(kbox[2] * axb);
 
    n[0] = 0;
    n[1] = 0;
    n[2] = 0;
    while (n[0] * proja <= cutoffRadius) n[0]++;
    while (n[1] * projb <= cutoffRadius) n[1]++;
    while (n[2] * projc <= cutoffRadius) n[2]++;
 
    return;
}

References kbox, and n.

Referenced by setup().

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Member Data Documentation

kspaceSolver

KSPACESolver nnp::KspaceGrid::kspaceSolver

Method for calculating the reciprocal part.

Definition at line 54 of file Kspace.h.

eta

double nnp::KspaceGrid::eta

Ewald summation eta parameter.

Definition at line 56 of file Kspace.h.

Referenced by KspaceGrid(), and setup().

kCut

double nnp::KspaceGrid::kCut

Cutoff in reciprocal space.

Definition at line 58 of file Kspace.h.

Referenced by KspaceGrid(), and setup().

rCut

double nnp::KspaceGrid::rCut

Cutoff in real space.

Definition at line 60 of file Kspace.h.

volume

double nnp::KspaceGrid::volume

Volume of real box.

Definition at line 62 of file Kspace.h.

Referenced by KspaceGrid(), and setup().

pre

double nnp::KspaceGrid::pre

Ewald sum prefactor \(\frac{2\pi}{V}\).

Definition at line 64 of file Kspace.h.

Referenced by KspaceGrid(), and setup().

n

int nnp::KspaceGrid::n[3]

Required box copies in each box vector direction.

Definition at line 66 of file Kspace.h.

Referenced by calculatePbcCopies(), and setup().

kbox

Vec3D nnp::KspaceGrid::kbox[3]

Reciprocal box vectors.

Definition at line 68 of file Kspace.h.

Referenced by calculatePbcCopies(), and setup().

kvectors

std::vector<Kvector> nnp::KspaceGrid::kvectors

Vector containing all k-vectors.

Definition at line 70 of file Kspace.h.

Referenced by nnp::Structure::calculateDAdrQ(), nnp::Structure::calculateElectrostaticEnergy(), and setup().

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The documentation for this class was generated from the following files:

• /home/runner/work/n2p2/n2p2/src/libnnp/Kspace.h
• /home/runner/work/n2p2/n2p2/src/libnnp/Kspace.cpp