From 3340ddf5a2e09e19e5be95fab019d7d9192eb920 Mon Sep 17 00:00:00 2001
From: Ayesha <ayeshamohottala@gmail.com>
Date: Thu, 30 Apr 2026 15:24:51 +0530
Subject: [PATCH] Update sigma and epsilon calculations with np.maximum

---
 ffprime/nb.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/ffprime/nb.py b/ffprime/nb.py
index 093b740..5c3eb1a 100644
--- a/ffprime/nb.py
+++ b/ffprime/nb.py
@@ -48,8 +48,8 @@ def __init__(self, atnums=None, atcharges=None, atvolumes=None, ref_atvolumes=No
             c6s_eff[i] = (volume_ratios[i])**2 * Element(atnum).c6["chu"]
             a_eff[i]  = (volume_ratios[i])    * Element(atnum).pold["chu"]
 
-            sigma[i] = (5.08 * a_eff[i]**(1/7)) / (2**(1/6)) / nanometer
-            epsilon[i] = c6s_eff[i] / (2 * (5.08 * a_eff[i]**(1/7))**6) / kjmol
+            sigma[i] = np.maximum(0.1, (5.08 * a_eff[i]**(1/7)) / (2**(1/6)))
+            epsilon[i] = np.maximum(0.0, c6s_eff[i] / (2 * (sigma[i] * (2**(1/6)))**6))
 
         # Store computed parameters
         self.atnums = atnums