We study the thermal breakage of a discrete one-dimensional string, with open and fixed ends, in the heavily damped regime. Basing our analysis on the multidimensional Kramers escape theory, we are able to make analytical predictions on the mean breakage rate, and on the breakage propensity with respect to the breakage location on the string. We then support our predictions with numerical simulations.PACS numbers: 82.20.Uv, 02.50.Ey Recently, there is much discussion on the possibility of exploiting biopolymers as functional materials [1,2,3,4]. To achieve this goal, the stabilities of such materials have to be thoroughly investigated. Furthermore, the facts that the biopolymers are necessarily finite and consist of discrete parts, such as individual peptides in an amyloid fibril [2], have to be taken into consideration. As a step towards this direction, we study here a toy model for the breakage of a discrete one-dimensional string under thermal fluctuations, in both fixed-ended and openended configurations (c.f. Fig. 1). This problem has been studied previously by numerical simulations [5,6,7] and theoretically with phenomenological assumptions on the effect of friction on the collective modes [8,9]. Multidimensional Kramers escape theory has also been applied to the study of breakage in a one-dimensional ring [10]. The energy profile for the bonds in the string is usually modeled by a quadratic potential at the minimum energy region, and by an inverted quadratic potential at the breakage point. Here, we employ a simplified model where all bonds are assumed to be Hookian up to the breakage point. This model has the virtue of rendering the theoretical analysis asymptotically exact as temperature goes to zero. By studying in detail the energy dependency on the collective modes, we are able to employ the multidimensional Kramers escape theory to predict the breakage rate and the breakage propensity with respect to the breakage location. These predictions are then verified by numerical simulations.A. String with fixed ends