Changes

waterwithoutmoon1 · Sep 12, 2024 · d4e267b · d4e267b
1 parent a56fba3
commit d4e267b
Showing 1 changed file with 153 additions and 0 deletions.
diff --git a/tests/test_berendsen_thermostat.cpp b/tests/test_berendsen_thermostat.cpp
@@ -0,0 +1,153 @@
+#include "atoms.h"
+#include "berendsen_thermostat.h"
+#include <gtest/gtest.h>
+
+TEST(BerendsenThermostatTest, NoTemperatureChange) {
+    // Create atoms with known velocities
+    const size_t n = 5;
+
+    Positions_t positions(3, n);
+    positions << 0.0, 1.0, 2.0, 3.0, 4.0,
+        0.0, 1.0, 2.0, 3.0, 4.0,
+        0.0, 1.0, 2.0, 3.0, 4.0;
+
+    Velocities_t velocities(3, n);
+    velocities.setOnes();
+
+    Atoms atoms{positions, velocities};
+
+    // Set up the test environment
+    double target_temperature = 1.0;
+    double timestep = 0.001;
+    double relaxation_time = 0.1;
+    double kB = 1;
+    double mass = 1;
+
+    double temperature = (2.0 * compute_kinetic_energy(atoms.velocities, mass)) / (3.0 *  atoms.nb_atoms() * kB);
+    // Check the temperature before applying the thermostat
+    EXPECT_NEAR(temperature, target_temperature, 1e-6);
+
+    // Apply the Berendsen thermostat
+    apply_berendsen_thermostat(atoms, kB, mass, target_temperature, relaxation_time,timestep);
+
+    // Check that velocities are scaled correctly
+    EXPECT_NEAR(atoms.velocities(0, 0), 1, 1e-6);
+    EXPECT_NEAR(atoms.velocities(1, 0), 1, 1e-6);
+    EXPECT_NEAR(atoms.velocities(2, 0), 1, 1e-6);
+
+    EXPECT_NEAR(atoms.velocities(0, 1), 1, 1e-6);
+    EXPECT_NEAR(atoms.velocities(1, 1), 1, 1e-6);
+    EXPECT_NEAR(atoms.velocities(2, 1), 1, 1e-6);
+
+    EXPECT_NEAR(atoms.velocities(0, 2), 1, 1e-6);
+    EXPECT_NEAR(atoms.velocities(1, 2), 1, 1e-6);
+    EXPECT_NEAR(atoms.velocities(2, 2), 1, 1e-6);
+
+    EXPECT_NEAR(atoms.velocities(0, 3), 1, 1e-6);
+    EXPECT_NEAR(atoms.velocities(1, 3), 1, 1e-6);
+    EXPECT_NEAR(atoms.velocities(2, 3), 1, 1e-6);
+
+    EXPECT_NEAR(atoms.velocities(0, 4), 1, 1e-6);
+    EXPECT_NEAR(atoms.velocities(1, 4), 1, 1e-6);
+    EXPECT_NEAR(atoms.velocities(2, 4), 1, 1e-6);
+}
+
+TEST(BerendsenThermostatTest, TemperatureDecrease) {
+    // Create atoms with known velocities
+    const size_t n = 5;
+
+    Positions_t positions(3, n);
+    positions << 0.0, 1.0, 2.0, 3.0, 4.0,
+        0.0, 1.0, 2.0, 3.0, 4.0,
+        0.0, 1.0, 2.0, 3.0, 4.0;
+
+    Velocities_t velocities(3, n);
+    velocities.setOnes();
+
+    Atoms atoms{positions, velocities};
+
+    // Set up the test environment
+    double target_temperature = 0.9;
+    double timestep = 0.001;
+    double relaxation_time = 0.1;
+    double kB = 1;
+    double mass = 1;
+
+    double temperature = (2.0 * compute_kinetic_energy(atoms.velocities, mass)) / (3.0 *  atoms.nb_atoms() * kB);
+    // Check the temperature before applying the thermostat
+    EXPECT_NEAR(temperature, target_temperature, 0.1);
+
+    // Apply the Berendsen thermostat
+    apply_berendsen_thermostat(atoms, kB, mass, target_temperature, relaxation_time,timestep);
+
+    // Check that velocities are scaled correctly
+    EXPECT_NEAR(atoms.velocities(0, 0), 0.9994998749374, 1e-6);
+    EXPECT_NEAR(atoms.velocities(1, 0), 0.9994998749374, 1e-6);
+    EXPECT_NEAR(atoms.velocities(2, 0), 0.9994998749374, 1e-6);
+
+    EXPECT_NEAR(atoms.velocities(0, 1), 0.9994998749374, 1e-6);
+    EXPECT_NEAR(atoms.velocities(1, 1), 0.9994998749374, 1e-6);
+    EXPECT_NEAR(atoms.velocities(2, 1), 0.9994998749374, 1e-6);
+
+    EXPECT_NEAR(atoms.velocities(0, 2), 0.9994998749374, 1e-6);
+    EXPECT_NEAR(atoms.velocities(1, 2), 0.9994998749374, 1e-6);
+    EXPECT_NEAR(atoms.velocities(2, 2), 0.9994998749374, 1e-6);
+
+    EXPECT_NEAR(atoms.velocities(0, 3), 0.9994998749374, 1e-6);
+    EXPECT_NEAR(atoms.velocities(1, 3), 0.9994998749374, 1e-6);
+    EXPECT_NEAR(atoms.velocities(2, 3), 0.9994998749374, 1e-6);
+
+    EXPECT_NEAR(atoms.velocities(0, 4), 0.9994998749374, 1e-6);
+    EXPECT_NEAR(atoms.velocities(1, 4), 0.9994998749374, 1e-6);
+    EXPECT_NEAR(atoms.velocities(2, 4), 0.9994998749374, 1e-6);
+}
+
+TEST(BerendsenThermostatTest, TemperatureIncrease) {
+    // Create atoms with known velocities
+    const size_t n = 5;
+
+    Positions_t positions(3, n);
+    positions << 0.0, 1.0, 2.0, 3.0, 4.0,
+        0.0, 1.0, 2.0, 3.0, 4.0,
+        0.0, 1.0, 2.0, 3.0, 4.0;
+
+    Velocities_t velocities(3, n);
+    velocities.setOnes();
+
+    Atoms atoms{positions, velocities};
+
+    // Set up the test environment
+    double target_temperature = 10.0;
+    double timestep = 0.001;
+    double relaxation_time = 0.1;
+    double kB = 1;
+    double mass = 1;
+
+    double temperature = (2.0 * compute_kinetic_energy(atoms.velocities, mass)) / (3.0 *  atoms.nb_atoms() * kB);
+    // Check the temperature before applying the thermostat
+    EXPECT_NEAR(temperature, target_temperature, 9);
+
+    // Apply the Berendsen thermostat
+    apply_berendsen_thermostat(atoms, kB, mass, target_temperature, relaxation_time,timestep);
+
+    // Check that velocities are scaled correctly
+    EXPECT_NEAR(atoms.velocities(0, 0), 1.044030650891, 1e-6);
+    EXPECT_NEAR(atoms.velocities(1, 0), 1.044030650891, 1e-6);
+    EXPECT_NEAR(atoms.velocities(2, 0), 1.044030650891, 1e-6);
+
+    EXPECT_NEAR(atoms.velocities(0, 1), 1.044030650891, 1e-6);
+    EXPECT_NEAR(atoms.velocities(1, 1), 1.044030650891, 1e-6);
+    EXPECT_NEAR(atoms.velocities(2, 1), 1.044030650891, 1e-6);
+
+    EXPECT_NEAR(atoms.velocities(0, 2), 1.044030650891, 1e-6);
+    EXPECT_NEAR(atoms.velocities(1, 2), 1.044030650891, 1e-6);
+    EXPECT_NEAR(atoms.velocities(2, 2), 1.044030650891, 1e-6);
+
+    EXPECT_NEAR(atoms.velocities(0, 3), 1.044030650891, 1e-6);
+    EXPECT_NEAR(atoms.velocities(1, 3), 1.044030650891, 1e-6);
+    EXPECT_NEAR(atoms.velocities(2, 3), 1.044030650891, 1e-6);
+
+    EXPECT_NEAR(atoms.velocities(0, 4), 1.044030650891, 1e-6);
+    EXPECT_NEAR(atoms.velocities(1, 4), 1.044030650891, 1e-6);
+    EXPECT_NEAR(atoms.velocities(2, 4), 1.044030650891, 1e-6);
+}