Write state file for minimum system energy

docs/_docs/analysis.md

@@ -645,7 +645,7 @@ All units in $k\_BT$.
 `file`         | Output filename (`.dat`, `.csv`, `.dat.gz`)
 `nstep`        | Interval between samples
 `nskip=0`      | Number of initial steps excluded from the analysis
-`save_min_conf=false` | Dump minimum energy configuration to `PQR` file
+`save_min_conf=false` | Dump minimum energy configuration to a `PQR` and state file
 
 
 ### Penalty function

docs/schema.yml

@@ -1203,7 +1203,7 @@ properties:
 
                 systemenergy:
                     properties:
-                        file: {type: string}
+                        file: {type: string, pattern: "(.*?)\\.(dat|dat.gz|csv)$", description: "Output filename (.dat|.dat.gz|.csv)"}
                         nstep: {type: integer}
                         nskip: {type: integer, default: 0, description: Initial steps to skip}
                         save_min_conf:

src/analysis.cpp

@@ -245,7 +245,8 @@ void SystemEnergy::normalize() {
 /**
  * @brief Checks if the current energy is the lowest so far and saves the configuration if so.
  *
- * The output is hardcoded to PQR format, tagged with the step number and energy.
+ * The output is hardcoded to PQR format, tagged with the step number and energy. In addition,
+ * we dump Space to a state file that can be used to restart a simulation.
  *
  * @return True if a new minimum energy was encountered
  */
@@ -254,9 +255,18 @@ bool SystemEnergy::updateMinimumEnergy(const double current_energy) {
         return false;
     }
     minimum_energy = current_energy;
-    const auto filename = MPI::prefix + "mininum_energy.pqr";
+
+    auto filename = MPI::prefix + "mininum_energy.pqr";
     faunus_logger->debug("{}: saving {} ({:.2f} kT) at step {}", name, filename, minimum_energy, getNumberOfSteps());
     PQRWriter(PQRWriter::Style::PQR).save(filename, spc.groups, spc.geometry.getLength());
+
+    filename = MPI::prefix + "mininum_energy.state";
+    if (std::ofstream file(filename); file) {
+        faunus_logger->debug("{}: saving {} ({:.2f} kT) at step {}", name, filename, minimum_energy, getNumberOfSteps());
+        json j;
+        Faunus::to_json(j, spc);
+        file << std::setw(1) << j;
+    }
     return true;
 }