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38 * Defines data structure and utilities for electric fields
40 * \author David van der Spoel <david.vanderspoel@icm.uu.se>
41 * \ingroup module_applied_forces
45 #include "electricfield.h"
52 #include "gromacs/commandline/filenm.h"
53 #include "gromacs/fileio/gmxfio.h"
54 #include "gromacs/fileio/xvgr.h"
55 #include "gromacs/math/units.h"
56 #include "gromacs/mdtypes/commrec.h"
57 #include "gromacs/mdtypes/forceoutput.h"
58 #include "gromacs/mdtypes/iforceprovider.h"
59 #include "gromacs/mdtypes/imdmodule.h"
60 #include "gromacs/mdtypes/imdoutputprovider.h"
61 #include "gromacs/mdtypes/imdpoptionprovider.h"
62 #include "gromacs/options/basicoptions.h"
63 #include "gromacs/options/ioptionscontainerwithsections.h"
64 #include "gromacs/options/optionsection.h"
65 #include "gromacs/utility/exceptions.h"
66 #include "gromacs/utility/keyvaluetreebuilder.h"
67 #include "gromacs/utility/keyvaluetreetransform.h"
68 #include "gromacs/utility/pleasecite.h"
69 #include "gromacs/utility/strconvert.h"
78 * \brief Describes an applied electric field in a coordinate
81 * Can compute the applied field strength at a time, and supports
82 * operations to read and form corresponding .mdp contents.
84 class ElectricFieldDimension
88 * Adds an option section to specify parameters for this field component.
90 void initMdpOptions(IOptionsContainerWithSections* options, const char* sectionName)
92 auto section = options->addSection(OptionSection(sectionName));
93 section.addOption(RealOption("E0").store(&a_));
94 section.addOption(RealOption("omega").store(&omega_));
95 section.addOption(RealOption("t0").store(&t0_));
96 section.addOption(RealOption("sigma").store(&sigma_));
97 if (sigma_ <= 0 && t0_ != 0.0)
100 InvalidInputError("Non-pulsed field (sigma = 0) ignores the value of t0. "
101 "Please, set t0 to 0 to avoid this error."));
105 * Creates mdp parameters for this field component.
107 void buildMdpOutput(KeyValueTreeObjectBuilder* builder, const std::string& name) const
109 builder->addUniformArray<real>("electric-field-" + name, { a_, omega_, t0_, sigma_ });
112 /*! \brief Evaluates this field component at given time.
114 * \param[in] t The time to evualate at
115 * \return The electric field
117 real evaluate(real t) const
121 return a_ * (std::cos(omega_ * (t - t0_)) * std::exp(-square(t - t0_) / (2.0 * square(sigma_))));
125 return a_ * std::cos(omega_ * t);
129 //! Return the amplitude
130 real a() const { return a_; }
133 //! Coeffient (V / nm)
137 //! Central time point (ps) for pulse
139 //! Width of pulse (ps, if zero there is no pulse)
144 * \brief Describe time dependent electric field
146 * Class that implements a force to be evaluated in mdrun.
147 * The electric field can be pulsed and oscillating, simply
148 * oscillating, or static, in each of X,Y,Z directions.
150 class ElectricField final : public IMDModule, public IMdpOptionProvider, public IMDOutputProvider, public IForceProvider
153 ElectricField() : fpField_(nullptr) {}
156 IMdpOptionProvider* mdpOptionProvider() override { return this; }
157 IMDOutputProvider* outputProvider() override { return this; }
158 void initForceProviders(ForceProviders* forceProviders) override
162 forceProviders->addForceProvider(this);
166 // From IMdpOptionProvider
167 void initMdpTransform(IKeyValueTreeTransformRules* transform) override;
168 void initMdpOptions(IOptionsContainerWithSections* options) override;
169 void buildMdpOutput(KeyValueTreeObjectBuilder* builder) const override;
171 // From IMDOutputProvider
172 void initOutput(FILE* fplog, int nfile, const t_filenm fnm[], bool bAppendFiles, const gmx_output_env_t* oenv) override;
173 void finishOutput() override;
175 // From IForceProvider
176 //! \copydoc IForceProvider::calculateForces()
177 void calculateForces(const ForceProviderInput& forceProviderInput,
178 ForceProviderOutput* forceProviderOutput) override;
180 void subscribeToSimulationSetupNotifications(MDModulesNotifiers* /* notifiers */) override {}
181 void subscribeToPreProcessingNotifications(MDModulesNotifiers* /* notifiers */) override {}
184 //! Return whether or not to apply a field
185 bool isActive() const;
187 /*! \brief Return the field strength
189 * \param[in] dim The spatial direction
190 * \param[in] t The time (ps)
191 * \return The field strength in V/nm units
193 real field(int dim, real t) const;
195 /*! \brief Print the field components to a file
197 * \param[in] t The time
198 * Will throw and exit with fatal error if file is not open.
200 void printComponents(double t) const;
202 //! The components of the applied electric field in each coordinate dimension
203 ElectricFieldDimension efield_[DIM];
204 //! File pointer for electric field
208 //! Converts dynamic parameters from new mdp format to (E0, omega, t0, sigma).
209 void convertParameters(gmx::KeyValueTreeObjectBuilder* builder, const std::string& value)
211 const std::vector<std::string> sxt = splitString(value);
218 GMX_THROW(InvalidInputError("Please specify E0 omega t0 sigma for electric fields"));
220 builder->addValue<real>("E0", fromString<real>(sxt[0]));
221 builder->addValue<real>("omega", fromString<real>(sxt[1]));
222 builder->addValue<real>("t0", fromString<real>(sxt[2]));
223 builder->addValue<real>("sigma", fromString<real>(sxt[3]));
226 void ElectricField::initMdpTransform(IKeyValueTreeTransformRules* rules)
228 rules->addRule().from<std::string>("/electric-field-x").toObject("/electric-field/x").transformWith(&convertParameters);
229 rules->addRule().from<std::string>("/electric-field-y").toObject("/electric-field/y").transformWith(&convertParameters);
230 rules->addRule().from<std::string>("/electric-field-z").toObject("/electric-field/z").transformWith(&convertParameters);
233 void ElectricField::initMdpOptions(IOptionsContainerWithSections* options)
235 auto section = options->addSection(OptionSection("electric-field"));
236 efield_[XX].initMdpOptions(§ion, "x");
237 efield_[YY].initMdpOptions(§ion, "y");
238 efield_[ZZ].initMdpOptions(§ion, "z");
241 void ElectricField::buildMdpOutput(KeyValueTreeObjectBuilder* builder) const
243 std::string comment =
245 ; Format for electric-field-x, etc. is: four real variables:
246 ; amplitude (V/nm), frequency omega (1/ps), time for the pulse peak (ps),
247 ; and sigma (ps) width of the pulse. Omega = 0 means static field,
248 ; sigma = 0 means no pulse, leaving the field to be a cosine function.)";
249 builder->addValue<std::string>("comment-electric-field", comment);
250 efield_[XX].buildMdpOutput(builder, "x");
251 efield_[YY].buildMdpOutput(builder, "y");
252 efield_[ZZ].buildMdpOutput(builder, "z");
255 void ElectricField::initOutput(FILE* fplog, int nfile, const t_filenm fnm[], bool bAppendFiles, const gmx_output_env_t* oenv)
259 please_cite(fplog, "Caleman2008a");
261 // Optional output file showing the field, see manual.
262 if (opt2bSet("-field", nfile, fnm))
266 fpField_ = gmx_fio_fopen(opt2fn("-field", nfile, fnm), "a+");
270 fpField_ = xvgropen(opt2fn("-field", nfile, fnm),
271 "Applied electric field",
280 void ElectricField::finishOutput()
282 if (fpField_ != nullptr)
284 // This is opened sometimes with xvgropen, sometimes with
285 // gmx_fio_fopen, so we use the least common denominator for closing.
286 gmx_fio_fclose(fpField_);
291 real ElectricField::field(int dim, real t) const
293 return efield_[dim].evaluate(t);
296 bool ElectricField::isActive() const
298 return (efield_[XX].a() != 0 || efield_[YY].a() != 0 || efield_[ZZ].a() != 0);
301 void ElectricField::printComponents(double t) const
303 fprintf(fpField_, "%10g %10g %10g %10g\n", t, field(XX, t), field(YY, t), field(ZZ, t));
306 void ElectricField::calculateForces(const ForceProviderInput& forceProviderInput,
307 ForceProviderOutput* forceProviderOutput)
311 const double t = forceProviderInput.t_;
312 const t_commrec& cr = forceProviderInput.cr_;
314 // NOTE: The non-conservative electric field does not have a virial
315 ArrayRef<RVec> f = forceProviderOutput->forceWithVirial_.force_;
317 auto chargeA = forceProviderInput.chargeA_;
318 for (int m = 0; (m < DIM); m++)
320 const real fieldStrength = gmx::c_fieldfac * field(m, t);
322 if (fieldStrength != 0)
324 // TODO: Check parallellism
325 for (int i = 0; i < forceProviderInput.homenr_; ++i)
327 // NOTE: Not correct with perturbed charges
328 f[i][m] += chargeA[i] * fieldStrength;
332 if (MASTER(&cr) && fpField_ != nullptr)
341 std::unique_ptr<IMDModule> createElectricFieldModule()
343 return std::make_unique<ElectricField>();