We present a new method for approximating two-body interatomic potentials from existing ab initio data based on representing the unknown function as an analytic continued fraction. In this study, our method was first inspired by a representation of the unknown potential as a Dirichlet polynomial, i.e., the partial sum of some terms of a Dirichlet series. Our method allows for a close and computationally efficient approximation of the ab initio data for the noble gases Xenon (Xe), Krypton (Kr), Argon (Ar), and Neon (Ne), which are proportional to $$r^{-6}$$
r
-
6
and to a very simple $$depth=1$$
d
e
p
t
h
=
1
truncated continued fraction with integer coefficients and depending on $$n^{-r}$$
n
-
r
only, where n is a natural number (with $$n=13$$
n
=
13
for Xe, $$n=16$$
n
=
16
for Kr, $$n=17$$
n
=
17
for Ar, and $$n=27$$
n
=
27
for Neon). For Helium (He), the data is well approximated with a function having only one variable $$n^{-r}$$
n
-
r
with $$n=31$$
n
=
31
and a truncated continued fraction with $$depth=2$$
d
e
p
t
h
=
2
(i.e., the third convergent of the expansion). Also, for He, we have found an interesting $$depth=0$$
d
e
p
t
h
=
0
result, a Dirichlet polynomial of the form $$k_1 \, 6^{-r} + k_2 \, 48^{-r} + k_3 \, 72^{-r}$$
k
1
6
-
r
+
k
2
48
-
r
+
k
3
72
-
r
(with $$k_1, k_2, k_3$$
k
1
,
k
2
,
k
3
all integers), which provides a surprisingly good fit, not only in the attractive but also in the repulsive region. We also discuss lessons learned while facing the surprisingly challenging non-linear optimisation tasks in fitting these approximations and opportunities for parallelisation.