Fix classic ABF in Tinker-HP

src/colvar.cpp

@@ -1752,7 +1752,7 @@ int colvar::calc_colvar_properties()
 
   } else {
 
-    if (is_enabled(f_cv_subtract_applied_force)) {
+    if (is_enabled(f_cv_subtract_applied_force) && !cvm::proxy->total_forces_same_step()) {
       // correct the total force only if it has been measured
       // TODO add a specific test instead of relying on sq norm
       if (ft.norm2() > 0.0) {
@@ -1839,7 +1839,8 @@ void colvar::update_extended_Lagrangian()
   // Integrate with slow timestep (if time_step_factor != 1)
   cvm::real dt = cvm::dt() * cvm::real(time_step_factor);
 
-  colvarvalue f_ext(fr.type()); // force acting on the extended variable
+  // Force acting on the extended variable
+  colvarvalue f_ext(fr.type());
   f_ext.reset();
 
   if (is_enabled(f_cv_external)) {

src/colvarbias.cpp

@@ -899,8 +899,9 @@ int colvarbias_ti::update_system_forces(std::vector<colvarvalue> const
   if ((cvm::step_relative() > 0) || proxy->total_forces_same_step()) {
     if (ti_avg_forces->index_ok(ti_bin)) {
       for (i = 0; i < num_variables(); i++) {
-        if (variables(i)->is_enabled(f_cv_subtract_applied_force)) {
+        if (variables(i)->is_enabled(f_cv_subtract_applied_force) || proxy->total_forces_same_step()) {
           // this colvar is already subtracting all applied forces
+          // or the "total force" is really a system force at current step
           ti_system_forces[i] = variables(i)->total_force();
         } else {
           ti_system_forces[i] = variables(i)->total_force() -

src/colvarbias_abf.cpp

@@ -459,8 +459,12 @@ int colvarbias_abf::update_system_force()
   // System force from atomic forces (or extended Lagrangian if applicable)
 
   for (i = 0; i < num_variables(); i++) {
-    if (colvars[i]->is_enabled(f_cv_subtract_applied_force)) {
+    if (colvars[i]->is_enabled(f_cv_subtract_applied_force) ||
+       (cvm::proxy->total_forces_same_step() && !colvars[i]->is_enabled(f_cv_external))) {
       // this colvar is already subtracting the ABF force
+      // or the "total force" is really a system force at current step
+      // (For external parameters, the total force contains biasing forces
+      // unless f_cv_subtract_applied_force is enabled)
       system_force[i] = colvars[i]->total_force().real_value;
     } else {
       system_force[i] = colvars[i]->total_force().real_value

src/colvarcomp_alchlambda.cpp

@@ -45,10 +45,11 @@ void colvar::alch_lambda::calc_value()
 {
   // By default, follow external parameter
   // This might get overwritten by driving extended dynamics
+  // (in apply_force() below)
   cvm::proxy->get_alch_lambda(&x.real_value);
 
   cvm::proxy->get_dE_dlambda(&ft.real_value);
-  ft.real_value *= -1.0; // Energy derivative to force
+  ft.real_value *= -1.0; // Convert energy derivative to force
 
   // Include any force due to bias on Flambda
   ft.real_value += cvm::proxy->indirect_lambda_biasing_force;
@@ -75,7 +76,6 @@ void colvar::alch_lambda::apply_force(colvarvalue const & /* force */)
 }
 
 
-
 colvar::alch_Flambda::alch_Flambda()
 {
   set_function_type("alch_Flambda");