diff --git a/gen_data.py b/gen_data.py
index 3c2daefb6932d743d7f972673a850aad68bd1b61..856ba8fbfd3293e49e7e884ac68eceb6ccdd8410 100644
--- a/gen_data.py
+++ b/gen_data.py
@@ -106,8 +106,11 @@ def gen_option_iter(steps=None, scale=None, **options):
     for index in np.ndindex(*steps):
         for key, (dim, array) in iter_variables.items():
             options[key] = array[index[dim]]
-        settings.logger.debug('step %s/%s: '%(index, steps) + ', '.join('%s=%s'%(key, value) for (key, value) in options.items() if key in iter_variables))
-        yield options.copy()
+        result = options.copy()
+        if "vac_omega" in result:
+            result["vac"] = result.pop("vac_omega") * result["omega"]
+        settings.logger.debug('step %s/%s: '%(index, steps) + ', '.join('%s=%s'%(key, value) for (key, value) in result.items() if key in iter_variables))
+        yield result
 
 
 def main():
@@ -219,6 +222,8 @@ python -m frtrg_kondo.gen_data \\
     fourier_coef_group = phys_group.add_mutually_exclusive_group()
     fourier_coef_group.add_argument("--vac", metavar='float', type=float, nargs='+', default=0.,
             help = "Vac, units of Tkrg")
+    fourier_coef_group.add_argument("--vac_omega", metavar='float', type=float, nargs='+',
+            help = "Vac/omega")
     fourier_coef_group.add_argument("--fourier_coef", metavar='tuple', type=float, nargs='*',
             help = "Voltage Fourier arguments, units of Tkrg")
     phys_group.add_argument("--fourier_phases", metavar='tuple', type=float, nargs='*',
@@ -359,16 +364,16 @@ python -m frtrg_kondo.gen_data \\
             if kondo_options["nmax"] < 0:
                 settings.logger.error(f"Invalid value nmax={nmax}: must be ≥0")
                 continue
-            settings.logger.info(f"Starting with Vdc={kondo_options['vdc']}, Vac={kondo_options['vac']}, Ω={kondo_options['omega']}, nmax={kondo_options['nmax']}")
+            settings.logger.info(f"Starting with Vdc={kondo_options['vdc']:.8g}, Vac={kondo_options['vac']:.8g}, Ω={kondo_options['omega']:.8g}, nmax={kondo_options['nmax']}")
             settings.logger.debug(kondo_options)
             settings.logger.debug(solver_options)
             kondo = Kondo(**kondo_options)
             kondo.run(**solver_options)
-            settings.logger.info(f"Saving Vdc={kondo_options['vdc']}, Vac={kondo_options['vac']}, Ω={kondo_options['omega']} to {filename}")
+            settings.logger.info(f"Saving Vdc={kondo_options['vdc']:.8g}, Vac={kondo_options['vac']:.8g}, Ω={kondo_options['omega']:.8g} to {filename}")
             kid, khash = dm.save_h5(kondo, filename, include)
             if find_pole:
                 pole, solver = kondo.findPole(**solver_options)
-                settings.logger.info(f"Saving pole for Vdc={kondo_options['vdc']}, Vac={kondo_options['vac']}, Ω={kondo_options['omega']} to database")
+                settings.logger.info(f"Saving pole for Vdc={kondo_options['vdc']:.8g}, Vac={kondo_options['vac']:.8g}, Ω={kondo_options['omega']:.8g} to database")
                 dm.save_pole(kid, khash, pole)
     else:
         # generate data points in parallel
@@ -407,7 +412,7 @@ def save_data_mp(queue, lock, solver_options, filename, include='all', find_pole
         if kondo_options["nmax"] < 0:
             settings.logger.error(f"Invalid value nmax={kondo_options['nmax']}: must be ≥0")
             continue
-        settings.logger.info(f"Starting with Vdc={kondo_options['vdc']}, Vac={kondo_options['vac']}, Ω={kondo_options['omega']}, nmax={kondo_options['nmax']}")
+        settings.logger.info(f"Starting with Vdc={kondo_options['vdc']:.8g}, Vac={kondo_options['vac']:.8g}, Ω={kondo_options['omega']:.8g}, nmax={kondo_options['nmax']}")
         settings.logger.debug(kondo_options)
         settings.logger.debug(solver_options)
         kondo = Kondo(**kondo_options)
@@ -415,13 +420,13 @@ def save_data_mp(queue, lock, solver_options, filename, include='all', find_pole
         lock.acquire()
         try:
             kid = -1
-            settings.logger.info(f"Saving Vdc={kondo_options['vdc']}, Vac={kondo_options['vac']}, Ω={kondo_options['omega']} to {filename}")
+            settings.logger.info(f"Saving Vdc={kondo_options['vdc']:.8g}, Vac={kondo_options['vac']:.8g}, Ω={kondo_options['omega']:.8g} to {filename}")
             kid, khash = dm.save_h5(kondo, filename, include, overwrite)
         finally:
             lock.release()
         if find_pole and kid >= 0:
             pole, solver = kondo.findPole(**solver_options)
-            settings.logger.info(f"Saving pole for Vdc={kondo_options['vdc']}, Vac={kondo_options['vac']}, Ω={kondo_options['omega']} to database")
+            settings.logger.info(f"Saving pole for Vdc={kondo_options['vdc']:.8g}, Vac={kondo_options['vac']:.8g}, Ω={kondo_options['omega']:.8g} to database")
             dm.save_pole(kid, khash, pole)