diff --git a/inc/eap_chain.jl b/inc/eap_chain.jl
index ba25799..5024520 100644
--- a/inc/eap_chain.jl
+++ b/inc/eap_chain.jl
@@ -82,6 +82,8 @@ function EAPChain(pargs::Dict)
                     InteractingEnergy();
                   elseif pargs["energy-type"] == "Ising"
                     IsingEnergy();
+                  elseif pargs["energy-type"] == "cutoff"
+                    UCutoff(pargs["cutoff-radius"]*pargs["mlen"])
                   else
                     error("energy-type is not understood.");
                   end,
@@ -144,6 +146,35 @@ function EAPChain(chain::EAPChain)
                  );
 end
 
+struct UCutoff <: Energy
+    cutoff_radius::Real;
+end
+
+# TODO: consider rewriting this to make better use of past calculations
+# this is probably by far the slowest calculation *shrug emoji*
+function (U_func::UCutoff)(chain::EAPChain)
+  crad2 = U_func.cutoff_radius * U_func.cutoff_radius;
+  U = 0.0;
+  @inbounds for i=1:n(chain)
+    @simd for j=i+1:n(chain) # once debugged, use inbounds
+      r = chain.xs[:, i] - chain.xs[:, j];
+      r2 = dot(r, r);
+      dU = if (r2 > crad2)
+          0.0
+      else
+          rmag = sqrt(r2);
+          r̂ = r / rmag;
+          r3 = r2*rmag;
+          μi = view(chain.μs, :, i);
+          μj = view(chain.μs, :, j);
+          (dot(μi, μj) - 3*dot(μi, r̂)*dot(μj, r̂)) / (4*π*r3);
+      end
+      U += dU;
+    end
+  end
+  return U;
+end
+
 # TODO: consider rewriting this to make better use of past calculations
 # this is probably by far the slowest calculation *shrug emoji*
 function U_interaction(chain::EAPChain)
diff --git a/mcmc_clustering_eap_chain.jl b/mcmc_clustering_eap_chain.jl
index f2b0e83..212088c 100644
--- a/mcmc_clustering_eap_chain.jl
+++ b/mcmc_clustering_eap_chain.jl
@@ -42,9 +42,13 @@ s = ArgParseSettings();
     default = 0.0
     help = "zero energy bond angle"
   "--energy-type", "-u"
-    help = "energy type (noninteracting|interacting|Ising)"
+    help = "energy type (interacting|cutoff|Ising|noninteracting)"
     arg_type = String
     default = "Ising"
+  "--cutoff-radius"
+    help = "cut off radius (units of monomer lengths)"
+    arg_type = Float64
+    default = 7.5
   "--kT", "-k"
     help = "dimensionless temperature"
     arg_type = Float64
diff --git a/run/phases-big_2023-05-18.jl b/run/phases-big_2023-05-18.jl
new file mode 100644
index 0000000..c7680b2
--- /dev/null
+++ b/run/phases-big_2023-05-18.jl
@@ -0,0 +1,49 @@
+println("Hello world!");
+
+@everywhere using Printf;
+
+@show workdir = if length(ARGS) > 0
+  ARGS[1];
+else
+  ".";
+end
+
+@everywhere fmt(x) = @sprintf("%07d", round(Int, 1e3*x));
+@everywhere fmt_int(x) = @sprintf("%03d", x);
+
+@everywhere function prefix(case)
+  "E0-$(fmt(case[:E0]))_K1-$(fmt(case[:K1]))_K2-$(fmt(case[:K2]))_kT-$(fmt(case[:kT]))_Fz-$(fmt(case[:Fz]))_Fx-$(fmt(case[:Fx]))_n-$(fmt(case[:n]))_b-$(fmt(case[:b]))_kappa-$(fmt(case[:kappa]))";
+end
+
+cases = Any[];
+κs = [0.0];
+Ks = zip([1.0; 0.0], [0.0; 1.0]);
+E0s = vcat(0.05:0.05:1.0, 1.5:0.5:5.0, 10.0);
+ns = Int[400];
+bs = [0.5; 1.0];
+kTs = [0.1; 1.0];
+Fs = zip([0.0; 1.0; 0.0; 1.0/sqrt(2.0)], [0.0; 0.0; 1.0; 1.0/sqrt(2.0)]);
+for b in bs, κ in κs, n in ns, Kvec in Ks, E0 in E0s, kT in kTs, F in Fs
+  K1, K2 = Kvec;
+  push!(cases, Dict(:E0 => E0, :K1 => K1, :K2 => K2,
+                    :kT => kT, :Fz => F[2], :kappa => κ,
+                    :Fx => F[1], :n => n, :b => b));
+end
+
+@info "total number of cases to run: $(length(cases))";
+
+mkpath(workdir);
+
+pmap(case -> begin;
+
+  outfile = joinpath(workdir, "$(prefix(case)).out");
+  if !isfile(outfile)
+    println("Running case: $case.");
+    command = `julia -O 3 mcmc_clustering_eap_chain.jl --chain-type cutoff --energy-type interacting -b $(case[:b]) --bend-mod $(case[:kappa]) --E0 $(case[:E0]) --K1 $(case[:K1]) --K2 $(case[:K2]) --kT $(case[:kT]) --Fz $(case[:Fz]) --Fx $(case[:Fx]) -n $(case[:n]) --num-steps 2000000 --burn-in 200000 -v 2 --prefix $(joinpath(workdir, prefix(case)))`;
+    output = read(command, String);
+    write(outfile, output); 
+  else
+    println("Case: $case has already been run.");
+  end
+
+end, cases);